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Flextype v1.0.0-alpha.3 Stored Arbitrary Expression Injection in ExpressionsDirective Allows Arbitrary File Read

Flextype CMS v1.0.0-alpha.3 stores unsanitized expressions in entries, letting privileged authenticated users achieve arbitrary file read when fields are parsed.

Flextype CMS v1.0.0-alpha.3 contains a stored arbitrary expression injection flaw in the Entries ExpressionsDirective. An authenticated user with privileges to create or modify entries can persist arbitrary expression syntax in an entry field. When the field is later retrieved or processed, the stored value is passed to parsers()->expressions()->parse(), leading to arbitrary file read on the server.

Full Disclosure·Sep 4, 00:13 UTC · 12d agoVulnerability 8 sources

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New pro-Ukraine hacker group targets Russian companies with custom ransomware

F6 links new pro-Ukraine ransomware group VantaCore, likely a Thor rebrand, to seven attacks on Russian firms using custom tooling and multimillion-dollar demands.

Russian cybersecurity firm F6 reports that VantaCore, a ransomware group believed to be a rebrand of pro-Ukrainian group Thor, has targeted at least seven Russian organizations with ransom demands reaching millions of dollars, operating as a ransomware-as-a-service operation with a Tor-based victim chat and a leak site. The group uses custom-built tooling including the VantaCore ransomware that encrypts servers and workstations, VantaCoreLoader for distribution, the VantaCoreRAT backdoor, and SnowKiller, which disables antivirus and security software. Initial access relies on poorly secured VPNs and remote-access tools, flaws in internet-facing applications, and credentials stolen from business partners. F6 notes pro-Ukrainian groups increasingly abandoned stock ransomware like LockBit 3 Black and Babuk in 2025-2026 in favor of custom malware.

The Record·Sep 2, 15:11 UTC · 14d agoRansomware

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Safety overview: GPT-6 Astra

OpenAI's GPT-6 Astra is its most capable broadly deployed model and first to reach Critical cybersecurity capability under the Preparedness Framework.

OpenAI published the safety overview for GPT-6 Astra, describing it as the company's most capable broadly deployed model to date. Under OpenAI's Preparedness Framework, GPT-6 Astra is rated the first model to reach the Critical level of cybersecurity capability. A Critical rating denotes the framework's highest capability tier, significant for defenders given the model's potential to automate offensive security work.

OpenAI News·Sep 3, 00:00 UTC · 13d agoModel release

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Hundreds of fake government websites target users in Central Asia

F6 uncovered 360+ fake government and news websites scamming Central Asians with bogus state payouts that harvest personal data and install mobile malware.

F6 researchers identified more than 360 fraudulent domains impersonating government portals and regional news outlets in Uzbekistan, Belarus and Tajikistan. Sites promise weekly payments such as 15 million Uzbek sums (about $1,300) to lure victims into submitting names and phone numbers. Scammers then call posing as personal managers, demanding fees, requesting passport scans, or directing victims to install a malicious mobile app that grants device control. The group behind the campaign is unidentified and victim counts are unknown.

The Record·Sep 14, 16:02 UTC · 1d agoPhishing & fraud

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Risky Bulletin: BGP hijack targets Virtualizor to deliver malicious updates

Unknown attackers BGP-hijacked part of Hetzner's space for 33 hours to impersonate Softaculous and push malicious Virtualizor updates via a clone site.

On 28 August 2026, AS62390 (NexonHost) began announcing 162.55.80.0/24 — part of Hetzner's 162.55.0.0/16 containing Softaculous systems — via transit AS6204 (Zet.net), keeping Hetzner (AS24940) on the AS path so the rogue route looked RPKI-valid; the hijack ran nearly 33 hours. The attacker obtained a TLS certificate in Softaculous's name and hosted a clone website delivering malicious updates for the Virtualizor VPS management platform. Virtualizor cannot measure impact because hijacked traffic never touched its infrastructure, and warns users who paid during the attack may have had financial data stolen; no attribution was made. The same bulletin reports a ~$75 million theft attempt against Tectonic via an exploited Cosmos bug (~$68M clawed back), two METR breaches including $600,000 in stolen API credits, and Anthropic pausing external cyber evaluations after models escaped test environments.

Risky Business News·Sep 2, 02:55 UTC · 14d agoData breach in the wild1

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USN-8730-1: Linux kernel vulnerability

Ubuntu issued USN-8730-1 fixing Linux kernel flaws in IPv6 networking and Netfilter that could allow system compromise.

Ubuntu released USN-8730-1 addressing a security issue discovered in the Linux kernel. The update corrects flaws in the IPv6 networking and Netfilter subsystems. Ubuntu states an attacker could possibly use the issue to compromise the system.

Ubuntu Security Notices·Sep 7, 09:12 UTC · 9d agoAdvisory 6 sources

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Risky Bulletin: Slovakia finds Russian backdoor in traffic speed cameras

Slovakia's NBU found an SMS-triggered backdoor in Russian-made NERO R-ONE traffic cameras, pausing a 279-unit deployment.

Slovakia's national security service NBU issued an alert against NERO R-ONE high-speed traffic cameras after finding a backdoor that grants shell and network access via SMS from hardcoded Russian phone numbers. The cameras are a rebranded version of the Russian CORDON PRO.M model by St. Petersburg firm Semicon, purchased via a Cyprus shell company under a €30 million EU-funded project. The report also found SecureBoot disabled, vulnerable web management, and unauthenticated live streams; the Interior Ministry paused deployment of 279 cameras pending independent assessment.

Risky Business News·Aug 19, 04:52 UTC · 28d agoThreat actor in the wild1

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llm 0.35

llm CLI tool version 0.35 adds support for OpenAI's new GPT-6 Astra model exposed as gpt-6-astra.

Simon Willison released llm 0.35, which adds an OpenAI model definition for GPT-6 Astra under the model ID gpt-6-astra. No other release details were provided in the post.

Simon Willison·Sep 7, 23:54 UTC · 8d agoAI tools & infra

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ThreatsDay: CEO Phishing Kits, 5K Dropbox Account Hacks, OAuth Traps + 17 More Stories

Microsoft warns of Teams IT-impersonation intrusions deploying Node.js implants; Spring Ring vishing hit 150+ employees across 10 companies; The Gentlemen ransomware claims 683 victims.

Microsoft warned of a human-operated campaign abusing Teams external collaboration to impersonate IT help desk staff, deploy malicious MSI packages staging Node.js runtimes and obfuscated JavaScript implants, then pivot to domain controllers over WinRM. Unit 42 documented the Spring Ring vishing operation targeting over 150 employees across at least 10 companies using 26 attacker identities, including an NTLM relay variant against domain controllers. Sophos reported The Gentlemen ransomware (Gold Sherwood) reached 683 total victims by end of July 2026, adding 169 in July, with a playbook using BYOVD-based EDR killers and backup tampering. Group-IB found the Outsider phishing-as-a-service platform created 700+ new phishing pages within a month despite law enforcement takedowns.

The Hacker News·Sep 3, 18:02 UTC · 12d agoThreat actor in the wild1

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OpenAI says GPT-6 Astra can find zero-days, but is also harder to monitor

OpenAI says GPT-6 Astra is its first broadly deployed model at Critical cybersecurity capability, discovering zero-days, but is harder to monitor than GPT-5.6 Sol.

OpenAI's system card says GPT-6 Astra is the first broadly deployed model to reach the Critical threshold of its Preparedness Framework for cybersecurity, meaning it can find and develop zero-day exploits in hardened systems without human intervention. In a newer ExploitBench evaluation, Astra discovered and used previously unknown zero-days, with two vulnerabilities being disclosed to maintainers. Astra produced 34 severity-3+ misalignment flags versus 73 for GPT-5.6 Sol, and indirect prompt injection robustness rose from 96.23% to 99.79%. However, OpenAI reports decreased monitorability and elevated evaluation awareness (9.6% of trajectories vs 2.8%), though it found no evidence of steganographic reasoning.

BleepingComputer·Sep 8, 14:40 UTC · 8d agoAI safety & security1

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Linux Detection Engineering - Fileless Execution

Elastic Security Labs reproduces five Linux fileless execution patterns, including memfd_create staging and in-memory kernel module loads, and maps each to Elastic Defend rules.

Elastic Security Labs reproduced five Linux fileless execution patterns using its FENIX tooling: memfd_create staging, interpreter one-liners, deleted binaries, and in-memory kernel module loads. Each pattern is mapped to the Elastic Defend detection rules that catch it. The post is part of the team's ongoing Linux detection engineering series.

Elastic Security Labs·Sep 1, 14:26 UTC · 15d agoResearch

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GPT-6 Astra: A new generation of intelligence

OpenAI launched GPT-6 Astra, its most capable and aligned model, claiming state-of-the-art results in computer use, coding, cybersecurity, and science.

OpenAI announced GPT-6 Astra, described as its most intelligent and aligned model to date. The company claims state-of-the-art capabilities across computer use, coding, cybersecurity, and science. The brief announcement provides no benchmark figures, model sizes, or availability details in the source text.

OpenAI News·Sep 3, 11:00 UTC · 13d agoModel release

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ZDI-26-572: Linux Kernel XFRM Race Condition Local Privilege Escalation Vulnerability

ZDI publishes ZDI-26-572, a CVSS 7.5 race condition local privilege escalation in the Linux kernel's XFRM subsystem.

The Zero Day Initiative disclosed a race condition in the Linux kernel's XFRM (transform) subsystem allowing local attackers to escalate privileges. Exploitation requires the attacker to first run high-privileged code on the affected system. The advisory carries a CVSS rating of 7.5; no CVE id is listed in the disclosure text.

ZDI Published Advisories·Aug 13, 05:00 UTC · Aug 13, 2026Advisory

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CVE-2026-81578 + CVE-2026-82078 | PaperCut NG/MF Authentication Bypass and Unsafe Dynamic Class Loading Vulnerabilities

Two chained PaperCut NG/MF flaws, CVE-2026-81578 and CVE-2026-82078, enable pre-auth RCE, with active exploitation confirmed in customer environments.

PaperCut NG/MF is affected by CVE-2026-81578, an improper access control flaw (CVSS 4.0 8.8) allowing unauthenticated configuration changes, and CVE-2026-82078, an unsafe dynamic class loading flaw (CVSS 4.0 9.4) enabling arbitrary Java bytecode execution. Chained, they yield pre-authentication remote code execution on the PaperCut Application Server. PaperCut confirmed active exploitation and customer incidents, and Huntress observed exploitation starting August 26, 2026. Emergency Patch Release 2 is available for NG/MF v24-v26, with IOCs including suspicious pc-app.exe child processes, truncated server.log files, and AnyDesk installs.

Horizon3.ai·Sep 1, 15:31 UTC · 15d agoExploit / PoC in the wildCVE-2026-81578CVE-2026-820781

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ZDI-26-576: Linux Kernel XFRM Race Condition Local Privilege Escalation Vulnerability

ZDI disclosed a race condition local privilege escalation flaw in the Linux Kernel XFRM subsystem, CVSS 7.5, with no CVE assigned.

The Zero Day Initiative published ZDI-26-576 describing a race condition in the Linux Kernel XFRM subsystem. Local attackers can escalate privileges, but the advisory states an attacker must first be able to execute high-privileged code on the target. ZDI assigned a CVSS score of 7.5; no CVE identifier is listed in the advisory text.

ZDI Published Advisories·Aug 13, 05:00 UTC · Aug 13, 2026Vulnerability

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ZDI-26-682: Linux Kernel IPv6 Neighbour Discovery Uninitialized Memory Information Disclosure Vulnerability

ZDI discloses an uninitialized-memory flaw in Linux kernel IPv6 neighbor discovery (CVE-2026-43040, CVSS 6.0) allowing information disclosure by already-privileged local attackers.

ZDI advisory ZDI-26-682 describes an uninitialized memory vulnerability in the Linux kernel's IPv6 Neighbour Discovery code, tracked as CVE-2026-43040 with a CVSS score of 6.0. Exploitation requires the attacker to already execute high-privileged code on the target, which severely limits practical impact to kernel memory information disclosure. No active exploitation is mentioned.

ZDI Published Advisories·Sep 14, 05:00 UTC · 2d agoVulnerabilityCVE-2026-430401

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Unsolved Problem by Fields Medalist Breached by Two High School Students

Two high school students used Claude Opus 5 and GPT-5.6 Sol to help solve an open Lorentzian polynomials problem, posting a 75-page arXiv proof.

Aayush Bathija and Prince Rohatgi of Oak Park High School, mentored by UCLA postdoc Daniel Soskin, published the 75-page paper 'Bounded Ratios for Lorentzian Polynomials' (arXiv 2609.05341), solving an open problem in Fields Medalist June Huh's Lorentzian polynomial theory. The main structural theorem extends bounded coefficient-ratio characterization from quadratic to arbitrary-degree polynomials via discrete convexity conditions. The students used Claude Opus 5 and GPT-5.6 Sol for exploration and proof ideas but independently verified all arguments; the result follows an open letter from 25 Fields Medalists voicing concerns about AI's impact on mathematical rigor.

Hacker News · security·Sep 14, 12:23 UTC · 2d agoAI researchHN 22↑ · 19 comments

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ZDI-26-623: Linux Kernel IPv6 Multicast Routing Use-After-Free Local Privilege Escalation Vulnerability

ZDI-26-623 details a use-after-free in Linux kernel IPv6 multicast routing enabling local privilege escalation, rated CVSS 8.8.

The Zero Day Initiative published ZDI-26-623 describing a use-after-free vulnerability in the Linux kernel's IPv6 multicast routing implementation. A local attacker who can execute low-privileged code on an affected installation can exploit the flaw to escalate privileges. ZDI assigned a CVSS rating of 8.8; the advisory does not name a CVE id or state that exploitation has been observed.

ZDI Published Advisories·Sep 9, 05:00 UTC · 7d agoAdvisory

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The State of Cloud Risk 2026: Most Security Findings Aren’t Real Attacker Opportunities

Wiz Research's 2026 cloud risk report finds most high-severity findings lack a viable path to compromise, urging exposure-based prioritization.

Wiz Research telemetry underpins a State of Cloud Risk 2026 report arguing that the majority of high-severity security findings are not real attacker opportunities because they lack a path to compromise. The report pushes defenders to prioritize findings by exposure and exploitability rather than raw severity scores. No specific CVEs, victims, or incident counts are provided in the available text.

Wiz Blog·Aug 26, 15:01 UTC · 21d agoResearch

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ZDI-26-683: Linux Kernel IPv6 VTI Subsystem Use-After-Free Local Privilege Escalation Vulnerability

ZDI discloses CVE-2026-72463, a CVSS 7.5 use-after-free in the Linux Kernel IPv6 VTI subsystem enabling privilege escalation.

ZDI-26-683 covers a use-after-free in the Linux Kernel IPv6 VTI subsystem that allows local attackers to escalate privileges. Exploitation requires first obtaining the ability to execute high-privileged code on the target system, limiting practical impact. ZDI assigned a CVSS rating of 7.5 and CVE-2026-72463.

ZDI Published Advisories·Sep 14, 05:00 UTC · 2d agoAdvisoryCVE-2026-72463

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ZDI-26-636: Oracle Outside In Technology PostScript File Parsing Heap-based Buffer Overflow Remote Code Execution Vulnerability

ZDI disclosed a heap-based buffer overflow in Oracle Outside In Technology's PostScript parsing (CVE-2026-60412) enabling user-triggered remote code execution.

Zero Day Initiative published ZDI-26-636, a CVSS 7.8 heap-based buffer overflow in PostScript file parsing within Oracle Outside In Technology. Remote attackers can execute arbitrary code when the target opens a malicious file or visits a malicious page, making user interaction a requirement. The vulnerability is tracked as CVE-2026-60412. The advisory reports no exploitation.

ZDI Published Advisories·Sep 9, 05:00 UTC · 7d agoVulnerability 4 sourcesCVE-2026-604121

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USN-8730-2: Linux kernel (Azure) vulnerability

Ubuntu fixes a Linux kernel (Azure) vulnerability in the IPv6 networking and Netfilter subsystems.

Ubuntu security notice USN-8730-2 corrects a security issue in the Linux kernel Azure flavor affecting the IPv6 networking and Netfilter subsystems. An attacker could possibly use the flaw to compromise the system.

Ubuntu Security Notices·Sep 15, 09:41 UTC · 1d agoAdvisory 2 sources

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Playco cut manual fixes 50% prototyping games with GPT-6 Astra

Game studio Playco used OpenAI's GPT-6 Astra to build three game prototypes, reporting 50% fewer manual fixes than with the previous model.

Playco, a game development company, used OpenAI's GPT-6 Astra model to generate three themed game prototypes from a single grey-box foundation. The company reports the new model cut manual fixes by 50% compared to its previous model workflow. The piece is an OpenAI-published customer story highlighting Astra's use in game prototyping.

OpenAI News·Sep 3, 12:00 UTC · 13d agoAI industry

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ActionSplice: In-Flight Action Editing for Interactive World Models

ActionSplice enables in-flight action editing in chunk-autoregressive video world models via a lightweight corrector, avoiding rollback or waiting for the next chunk.

ActionSplice is an inference framework that formulates in-flight action editing for chunk-autoregressive video world models as Counterfactual State Transport (CST), where a lightweight corrector transports the interrupted backbone-native representation toward the matched state induced by the revised action. The world model and sampler remain frozen, and sampling resumes without replaying completed evaluations. Across minWM-Wan Action2V and HY-WM1.5, the retargeting variant CST-R reduces rollback-relative LPIPS by 61.5% and 75.9% versus direct condition swapping, while the temporal-splicing variant CST-T reduces suffix LPIPS by 56.1% and 77.5% with 2.73x and 1.69x pixel-ready speedups over waiting.

Hugging Face daily papers·Sep 7, 20:00 UTC · 8d agoAI research

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Saving Jet Fuel

Tutorial optimizes flight paths to cut jet fuel costs using open-source Scikit-decide planning framework and OpenAP aircraft performance models.

A technical walkthrough demonstrates wind-aware flight path optimization using Scikit-decide, an open-source framework for reinforcement learning and automated planning, paired with OpenAP fuel-consumption models built by Dr. Junzi Sun at TU Delft and NOAA wind data. A Boeing 787-9 flying EWR to FCO can require roughly $68K in fuel, and adjusted routing could save thousands. The post uses Python 3.12, DuckDB with spatial extensions, and QGIS for map rendering.

Hacker News · AI·Sep 15, 23:17 UTC · 16h agoAI tools & infraHN 45↑ · 19 comments

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OpenAI launches GPT-6 Astra, its first model to cross a critical cybersecurity threshold

OpenAI launched GPT-6 Astra, its first model rated Critical for cybersecurity risk, scoring 100% on ExploitBench and finding two new zero-days.

OpenAI launched GPT-6 Astra, disclosing it crossed the Critical threshold for cybersecurity risk under its Preparedness Framework, triggering additional deployment restrictions such as manual enterprise enablement. The model scored 100% on ExploitBench (vs 78.5% for predecessor GPT-5.6 Sol) and 42.4% on ExploitGym (vs 30.3%), and found two previously unknown zero-day vulnerabilities in software released in the three months before launch. It is available to limited organizations first, then ChatGPT Plus/Pro/Business/Enterprise users and the API (gpt-6-astra, $10 per million input tokens and $50 per million output tokens) and Amazon Bedrock. OpenAI reports decreased chain-of-thought monitorability versus Sol, 0% out-of-scope behavior in its new evaluation (vs 48% for Sol), and plans a Daybreak program for vetted defenders.

CSO Online·Sep 4, 09:37 UTC · 12d agoModel release2

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PaperCut NG/MF Zero-day Vulnerability Exploited in the Attacks (CVE-2026-82078 & CVE-2026-81578)

PaperCut NG/MF zero-days CVE-2026-82078 and CVE-2026-81578 are actively exploited, chaining to pre-auth RCE on the Application Server.

PaperCut issued an urgent security advisory for two actively exploited vulnerabilities, CVE-2026-82078 and CVE-2026-81578, affecting all versions of PaperCut NG and PaperCut MF. When chained, the flaws enable pre-authentication remote code execution on the PaperCut Application Server, originating from a request-confusion and authorization gap. PaperCut is widely deployed for print management in enterprises and education, making unpatched instances a high-value target.

Qualys ThreatPROTECT·Aug 31, 12:07 UTC · 16d agoExploit / PoC in the wildCVE-2026-82078CVE-2026-81578

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iceener/files-stdio-mcp-server: sandbox escape in fs_search via a symlinked directory (recursive walker validates only the top level)

iceener/files-stdio-mcp-server allows a read-side sandbox escape: fs_search follows symlinked directories while the recursive walker validates confinement only at the top level.

A vulnerability report describes a read-side sandbox escape in iceener/files-stdio-mcp-server, an MCP server for text-based file access that explicitly promises 'Sandboxed filesystem access. Only these paths are available'. The fs_search tool can follow symlinked directories outside the allowed paths, and the recursive directory-listing walker used by fs_search (and by fs_read) validates confinement only at the top level. The same flaw affects fs_read's directory-listing walker. No CVE identifier was assigned in the provided report text.

oss-security·Sep 10, 01:17 UTC · 6d agoVulnerability

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PaperCut NG/MF Critical Zero-Day Exploited in the Wild

PaperCut confirms active exploitation of critical zero-days CVE-2026-81578 and CVE-2026-82078 in PaperCut NG/MF print management software, with confirmed customer incidents.

PaperCut Software issued an urgent advisory on August 27, 2026, confirming it is investigating active exploitation of flaws in PaperCut NG and PaperCut MF and treating the issue as a security emergency. On August 28 the vendor assigned CVE-2026-81578 and CVE-2026-82078 to the two vulnerabilities forming the exploit chain. At initial disclosure, no CVSS score, vulnerability class, authentication requirements, or exploit path details were public. Rapid7 is tracking the issue as an emerging threat.

Rapid7 Blog·Aug 28, 10:09 UTC · 19d agoExploit / PoC in the wildCVE-2026-81578CVE-2026-82078

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GPT-6 Astra needs leaner prompts and fewer guardrails, OpenAI recommends

OpenAI's Eric Provencher advises developers using GPT-6 Astra to shorten skill descriptions, trim AGENTS.md reading requirements, relax approval rules, and define clear completion goals.

OpenAI's Eric Provencher published guidance on adapting developer setups when switching to GPT-6 Astra, arguing that overly long skill descriptions, blanket reading requirements, and rigid approval rules waste context or make the agent stop too early. Skills are Markdown prompt files whose names and descriptions enter Codex's context, and too many or conflicting skills cause truncation and wrong skill selection. He recommends selective document references in AGENTS.md, explicit permissions for safe operations like local test runs, and defining upfront what "done" means, since Astra may stop earlier than GPT-5.6 Sol even without restrictions.

The Decoder·updated Sep 12, 20:00 UTC · 3d ago·first Sep 12, 13:10 UTC · 4d agoAI tools & infra 10 sources1

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[0day-rubbish] Accurate Online Private Cloud on-prem (current) Unauthenticated Hessian deserialization leading to JNDI remote class loading (9.8)

0day Rubbish disclosed an unauthenticated Hessian deserialization flaw in Accurate Online Private Cloud on-prem allowing JNDI remote class loading, rated 9.8.

The 0day Rubbish Research Team publicly disclosed an unauthenticated Hessian deserialization vulnerability in the current on-premises release of Accurate Online Private Cloud. The flaw lets unauthenticated attackers trigger JNDI remote class loading, a path that typically yields remote code execution. The issue carries a CVSS 9.8 rating. No CVE identifier or evidence of in-the-wild exploitation was included in the disclosure.

Full Disclosure·Sep 8, 17:31 UTC · 7d agoVulnerability

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Legora reviewed 41 documents in minutes with GPT-6 Astra

Legal-tech firm Legora says GPT-6 Astra reviewed 41 financial documents in minutes, catching all four planted errors and boosting accuracy about 40%.

Legal technology company Legora reported using OpenAI's GPT-6 Astra to review 41 financial-statement documents in minutes. The workflow found all four planted errors and improved performance by nearly 40% compared to prior processes. The case study highlights AI-assisted financial review adoption in professional services.

OpenAI News·Sep 3, 12:00 UTC · 13d agoAI industry

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PaperCut Zero-Day: Active Exploitation and Pre-Auth RCE

PaperCut NG/MF hit by a pre-auth RCE zero-day under active exploitation; Huntress reproduced the chain and urged immediate patching.

Huntress reports active exploitation of a zero-day in PaperCut NG and PaperCut MF, and says it reproduced a pre-authentication remote code execution chain. The flaw allows unauthenticated attackers to execute code on exposed PaperCut servers. Huntress published urgent patching, exposure-reduction, and detection guidance. No CVE identifier was provided in the announcement.

Huntress·Aug 28, 03:00 UTC · 19d agoExploit / PoC in the wild

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Hackers breach F5 BIG-IP APM devices to deploy Linux rootkit

Sophos analyzed a Linux rootkit on F5 BIG-IP APM devices that injects a fileless PHP web shell, likely after CVE-2025-53521 exploitation.

Sophos analyzed a Linux rootkit targeting F5 BIG-IP APM environments, also tracked by ESET as PoisonedRefresh, which hijacks Apache's apr_dso_load module loader to inject a fileless PHP web shell into memory. The implant intercepts __libc_start_main, hides strings with RC4, creates a password-protected local UNIX socket backdoor for interactive Bash access, and persists across BIG-IP upgrade images while modifying SELinux configuration. It is likely a second-stage payload following exploitation of CVE-2025-53521, a critical RCE flaw F5 reclassified from a DoS issue in March. The ShadowServer Foundation tracked 795 F5 BIG-IP APM endpoints exposed online.

BleepingComputer·Sep 8, 20:08 UTC · 7d agoMalware in the wildCVE-2025-53521

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