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ZDI-26-627: Backblaze Personal Computer Backup bztransmit Link Following Denial-of-Service Vulnerability

ZDI published ZDI-26-627 for a local denial-of-service flaw (CVE-2026-19820, CVSS 6.1) in Backblaze Personal Computer Backup's bztransmit component.

The Zero Day Initiative published advisory ZDI-26-627 describing a link-following denial-of-service vulnerability in the bztransmit component of Backblaze Personal Computer Backup. Local attackers must first execute low-privileged code on the target system to trigger the condition. The issue carries a CVSS score of 6.1 and is tracked as CVE-2026-19820.

Re: Retrospective by 'gpg.fail' authors

Peter Gutmann replies to gpg.fail retrospective, pointing to PGP's arbitrary packet format as root of many past vulnerabilities.

Peter Gutmann posted a follow-up on oss-security referencing an Hacker News discussion of the gpg.fail authors' retrospective. The thread argues that a recurring source of severe PGP vulnerabilities is the format's permissive packet system, where a PGP message is a practically arbitrary stream of packets. This is discussion and retrospective analysis rather than a new disclosure.

oss-securityupdated · 2h agofirst · 3d agoResearch 9 sources4

Most Firms Unable to Recover Quickly from Ransomware

Fenix24's first State of Recoverability report finds only 0.5% of 800+ ransomware clients neared 24-48 hour recovery targets, with identity failures central.

Drawing on 500+ ransomware recoveries, Fenix24 found only four of 800+ clients (0.5%) came close to their own 24-48 hour recovery targets, and none reached full operations for weeks. 99.2% lacked a documented identity recovery plan, Active Directory typically fell first, and 94% tied backup systems to the compromised directory. In 38% of engagements backups survived but could not carry recovery; storage ran short in 82% of cases and 95% lacked meaningful MFA on critical infrastructure consoles.

Infosecurity Magazine · 1d agoResearch

BTR Reforged: Weaponizing Defender’s Remediation Driver as a Kernel Operation Primitive

Check Point shows attackers can abuse Microsoft Defender's signed remediation driver for arbitrary Ring 0 file and registry operations without exploiting any vulnerability.

Check Point Research presents BTR Reforged, a technique that repurposes Microsoft Defender's trusted remediation driver into an attacker-controlled kernel operation primitive. The signed driver can be instructed to execute arbitrary file and registry operations from Ring 0 without exploits, vulnerabilities, or memory corruption. The work demonstrates how trusted security components can be turned into attacker primitives, which is relevant for defenders assessing driver abuse risks.

Check Point Research · 27d agoResearch

Plesk Backup Manager Flaw Lets Low-Privileged Users Gain Root Access to Servers

CVE-2026-68488 in Plesk Backup Manager lets low-privileged subscription users exploit a symlink race during restores to gain root on Linux servers.

CVE-2026-68488 is a symlink race condition in Plesk Obsidian for Linux Backup Manager during subscription-content restore operations, allowing a user with Panel and FTP access to change ownership of files outside their subscription and escalate to full root access. Affected versions are Plesk for Linux 18.0.80.6 and earlier and 18.0.79.10 and earlier; Plesk for Windows is not affected. Patches are available in 18.0.80.7 and 18.0.79.11 or later. The flaw requires valid subscription access, so it is not unauthenticated remote code execution, but successful exploitation yields complete server compromise, especially dangerous in shared-hosting and multi-tenant deployments.

Enterprise Defenses Recovered at the Edge and Collapsed Inside

Picus Labs' Blue Report 2026 finds perimeter prevention at 69% but post-compromise prevention just 37%, with reconnaissance blocked only 10% of the time.

Picus Labs' Blue Report 2026, based on 434,000+ simulated attacks across client production environments in H1 2026, found perimeter prevention effectiveness rose from 62% to 69% while the Post-Compromise Prevention Rate was only 37%. Quiet techniques fared worst: reconnaissance was blocked 10% of the time, registry-based credential access less than 1%, and the alert score stayed at 14% despite logging at a four-year high of 58%. IOC-based prevention fell to 50% from 71% in 2024, and Mimikatz's LSASS path was blocked about 94% while alternative credential-read paths went nearly undetected.

The Hacker News · Aug 12, 2026Research

MFA's Weakest Link: Account Recovery Is the New Attack Path

Help desk account recovery is increasingly the weakest link in MFA-protected identities, as Scattered Spider's impersonation-driven Marks & Spencer attack demonstrated.

As MFA, conditional access, and phishing-resistant factors raise the cost of direct account takeover, attackers increasingly target the recovery process, convincing service desk staff to reset passwords or re-register MFA on attacker-controlled devices. CISA, FBI, and partner advisories describe Scattered Spider posing as employees to trigger such resets; the 2025 Marks & Spencer attack began this way and led to ransomware with an estimated £300 million profit impact. Microsoft now describes Entra ID account recovery as a high-assurance process, and the article promotes Specops Secure Service Desk for verified identity workflows.

BleepingComputer · 7d agoPhishing & fraud

Trusting-Trust Attack against an Entire Linux Distribution (via the strip utility)

ArXiv paper shows the trusting-trust compiler backdoor technique can compromise an entire Linux distribution via the strip utility.

The paper (arXiv 2607.24888) demonstrates that Ken Thompson's trusting-trust attack, long viewed as a compiler-specific threat, can backdoor an entire Linux distribution by targeting the strip utility. A compromised tool reproduces its backdoor in subsequent rebuilds of itself, generalizing the attack surface beyond compilers. The finding has supply-chain implications for build reproducibility and distribution trust, though it is a research result with no observed real-world exploitation.

Lobsters · security · 11d agoResearch

New Passkey Attacks Can Recover Synced Private Keys or Bypass Phishing

Three research teams showed passkey bypasses: WebAuthn assertion replay in Microsoft Entra ID, synced-passkey key recovery in Google Password Manager, and Windows Hello key reuse.

SpecterOps' Pass-the-Passkey research showed Windows stored past YubiKey signatures in cleartext and chained this with Microsoft Entra ID passkey validation weaknesses to impersonate privileged users despite phishing-resistant MFA; the Windows Event Logging Service issue is tracked as CVE-2026-34348 (CVSS 6.5) and fixed in July 2026 updates. Unit 42's Golden Pass-ta-key attack recovered the 32-byte Security Domain Secret protecting Google Password Manager synced passkeys from Chrome on Windows via pre-existing malware. Dirk-jan Mollema showed in-session malware can use a hardware-bound Windows Hello for Business key without a fresh PIN or biometric check. Microsoft applied Entra-side mitigations for the relay assertion issue; no real-world exploitation has been reported.

The Hacker News · Aug 11, 2026VulnerabilityCVE-2026-34348

"They don't care about this": A Systematic Study of TEE Build Reproducibility in the Wild

91% of 115 surveyed TEE deployments across Intel SGX, TDX, and AMD SEV fail to provide reproducible builds needed for verifiable remote attestation.

A systematic study of 115 TEE deployments found 91% were not reproducible and 80% lacked both source code and a reference build, undermining remote attestation guarantees. Interviews with 12 developers of 50 Intel SGX projects confirmed that only one participant treats reproducibility as a development priority. The authors identify technical barriers such as embedded timestamps plus ecosystem-level issues like lack of build-environment control in multi-stakeholder projects, and call for holistic, committed reproducibility practices.

arXiv cs.CR · 6d agoResearch

TPMSpy: Validation of Measured Boot Systems by Low-Level Tracing of TPM Usage

Researchers present TPMSpy, a platform-agnostic method validating TPM Measured Boot via low-level tracing, finding inconsistent Linux systemd measurements that break remote attestation and LUKS decryption.

An arXiv paper (2609.05011) introduces TPMSpy, a method that analyzes virtualized system–TPM interactions to independently reconstruct and validate TPM Event Logs without relying on the quoting mechanism, applicable to open and closed systems and demonstrated on Linux and Windows. A longitudinal analysis of Linux systems running systemd versions 245–258 (2020–2025) found wide divergence in Measured Boot usage, undocumented behavioral changes, and no common usage pattern. The authors report inconsistent measurement of user-space systemd services, which prevents reliable remote attestation and LUKS disk decryption on affected systems.

arXiv cs.CR · 12d agoResearch

Decade-old PostgreSQL flaw turns backup account into a backdoor

Cyera disclosed CVE-2026-6471, a decade-old PostgreSQL flaw letting REPLICATION-attribute accounts achieve RCE and superuser compromise, patched August 13.

Cyera Research's 'PostGREShell' flaw exists in PostgreSQL's logical replication output plugin loading, where the replication code path never called the library-path security check, allowing path traversal or UNC paths to load arbitrary code. A low-privilege backup account can achieve code execution on Windows, Linux, and macOS, then escalate to superuser with persistent backdoor access. CVE-2026-6471 affects versions back to PostgreSQL 9.4 (2014) and was patched in releases 18.6, 17.11, 16.15, 15.19, and 14.24 on August 13. CVSS is 7.2, and no exploitation of this specific CVE has been confirmed, though VirusTotal hunting found 114 malicious PostgreSQL plugins.

CSO Online · 13d agoVulnerabilityCVE-2026-6471

Revoked but Still Authoritative: An Empirical Study of Revocation Enforcement in Agent-Memory Systems

An empirical study finds no major agent-memory system enforces fact revocation at retrieval, causing agents to act on superseded, unsafe information.

Researchers tested five agent-memory systems across nine policy scenarios, nine models, and six defense conditions, tracking whether revoked facts are returned and acted upon. No system enforces revocation by default: revoked records are returned whenever the revocation label is visible to the retrieval layer, outrank their replacements, and lead agents to unsafe actions. The authors propose a backend-agnostic guard that sits between the agent and any memory store and withholds revoked or conflicting records at retrieval time.

arXiv cs.CR · 9d agoAI safety & security

Does Your Agent's Memory Survive a Model Upgrade? A Controlled Study of Memory Portability

A controlled study finds agent memory portability varies sharply: fixed-schema knowledge graphs survive model swaps while compressed notes degrade.

The study compares preserving an agent's history as raw long context, RAG chunks, compressed natural-language notes, or fixed-schema knowledge graphs across model upgrades, using 48 synthetic histories and two open-weight sub-10B-parameter models. Fixed-schema KG accuracy changed by only +0.0004 ± 0.0020 after a writer swap, while compressed NOTES shifted asymmetrically by +9.91 or -13.28 percentage points depending on migration direction. Mixed 50/50 embedding migrations captured only 4.96 of an 11.90-point RAG re-embedding gain; 80% of the NOTES deficit came from information lost at construction, and 81% of the RAG deficit from retrieval failures. Store-only repair of NOTES failed to reach 90% recovery in all 48 cases, while retaining raw histories enabled recovery in 34 of 48 for one direction.

arXiv cs.AI / cs.LG / cs.CL · 12d agoAI research1

Forgetting Without Restarting: Execution-State Unlearning for Stateful LLM Agents

Researchers propose provenance-guided selective replay letting LLM agents forget revoked information without restarts, matching full reset behavior.

The paper formalizes execution-state unlearning for stateful LLM agents, requiring that agents behave as if a revoked memory record was never observed across transcripts, compressed memory, tool plans, and KV caches. It proves exact unlearning requires at least T-τ+1 recomputed transitions and that Provenance-Guided Selective Replay attains this bound via a provenance graph, KV cache cropping, and sanitized replay. In audits across three agent suites, nine baselines, and three model families, memory deletion left leakage unchanged, instruction-based forgetting collapsed under elicitation (Leak@probes = 1.00), and selective replay matched full resets at up to 9x fewer recomputed tokens.

arXiv cs.CR · 12d agoAI safety & security1