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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.
A public proof-of-concept exploit for an SSRF flaw in Linuxfabrik monitoring_plugins 6.0.0 appeared on Exploit-DB.
Exploit-DB listing 52653 discloses a server-side request forgery (SSRF) vulnerability in Linuxfabrik monitoring_plugins version 6.0.0, classified under web applications. A proof-of-concept exploit is publicly available. No CVE identifier or evidence of in-the-wild exploitation is provided in the listing.
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.
Sophos details PoisonedRefresh, a fileless Linux rootkit that injects a memory-resident PHP web shell into F5 BIG-IP APM after exploitation of CVE-2025-53521.
On September 8, 2026, SophosLabs published an analysis of Linux/Agnt-IC (dubbed PoisonedRefresh by ESET) found in compromised F5 BIG-IP Access Policy Manager environments. Initial access leverages CVE-2025-53521, an unauthenticated RCE in BIG-IP APM when an access policy is configured on a virtual server; F5 confirmed exploitation and links the activity to cluster c05d5254, while Shadowserver observed 795 exposed vulnerable endpoints. A first stage hidden in a modified umount binary modifies /usr/sbin/httpd and SELinux configuration and embeds itself in BIG-IP upgrade images for persistence. The second-stage ELF intercepts __libc_start_main, hooks apr_dso_load, and injects a PHP web shell into libphp memory via mmap manipulation, leaving no disk artifacts, and exposes a /bin/bash shell via a local UNIX domain socket instead of a TCP port.
Sophos analyzed a Linux rootkit, tracked as PoisonedRefresh, on hacked F5 BIG-IP APM devices hiding an in-memory web shell linked to exploited CVE-2025-53521.
Sophos and ESET analyzed an implant (named PoisonedRefresh by ESET) deployed on compromised F5 BIG-IP APM appliances, which serves enterprise, financial, government, and public sector deployments. The second-stage payload intercepts __libc_start_main, hooks Apache's APR module loader (apr_dso_load), RC4-encodes key strings, and rewrites PHP file reads in memory to embed a web shell inside legitimate scripts like apm_css.php3, full_wt.php3, and webtop_popup_css.php3, leaving on-disk files unchanged. A related installer component infects /usr/sbin/httpd, persists across BIG-IP upgrade images, modifies SELinux configuration, and deploys the payload. The malware also creates a Unix domain socket at /run/bigtlog.pipe that hands authenticated local connections to /bin/bash; F5 links the activity to CVE-2025-53521, an unauthenticated RCE in BIG-IP APM already exploited in the wild.
Rapid7 uncovered a DPRK-linked Linux toolkit using a HAProxy-embedded ted backdoor, SSH keylogger, and curlRAT against South Korean media and automotive firms.
Rapid7 Labs identified a previously undocumented framework attributed with medium confidence to DPRK actors, targeting South Korean automotive and media organizations likely since early 2025. The toolkit embeds a backdoor compiled into HAProxy 2.8.12 using its filter API, plus trojanized crond, agetty, atd, sshd, and polkitd, an SSH keylogger storing credentials under /var/lib/sshd/, and a curl-based RAT with a watchdog thread. It enables remote command execution, malicious script injection into served webpages (a watering-hole loop), credential harvesting, and long-term surveillance. Hardcoded C2s are associated with APT37 via ThreatFox, and exposed groupware portals and mail servers align with Kimsuky tradecraft; the initial access vector and any CVE remain unconfirmed.
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.
Sophos analyzed a stealth Linux rootkit that hides a web shell in memory on compromised F5 BIG-IP APM identity gateways, evading file-based detection.
Sophos analyzed a second-stage Linux rootkit implant found in compromised F5 BIG-IP APM environments running Apache and PHP, linked to exploitation of CVE-2025-53521, an unauthenticated RCE. The implant hooks Apache's PHP-loading process and serves modified in-memory versions of three legitimate webtop PHP files (apm_css.php3, full_wt.php3, webtop_popup_css.php3), leaving on-disk files untouched so hashes and integrity checks pass. It also establishes access via an authenticated local UNIX socket that can provide an interactive /bin/bash session. Experts warn compromised APM appliances, which handle federated SSO and terminate TLS at enterprise perimeters, could enable SSO token theft and lateral movement to trusted downstream applications.
Cisco Talos details ClearFake's fake-CAPTCHA chain deploying ZigCryptoStealer with a BYOVD attack that kills EDR processes, observed at a Ukrainian government organization in April 2026.
ClearFake compromises websites, injects JavaScript via a malicious Cloudflare Worker, retrieves instructions from BNB Smart Chain contracts (EtherHiding), and presents a fake Google CAPTCHA that tricks Windows users into pasting a command that loads a remote library over WebDAV via rundll32. The crypto-stealer branch uses DLL side-loading with a signed Chrome component to launch ZigCryptoStealer, which hijacks clipboard cryptocurrency addresses, alongside a signed but vulnerable Windows driver used in a BYOVD attack to terminate EDR processes. A parallel branch delivers Amatera secondary payloads that install a hidden remote-access client providing operator desktop control, with Cisco Talos tracking the remote-loader activity as UAT-10820. Talos observed unusual remote library execution at a Ukrainian government organization in April 2026 and assesses the attacks are part of a broader theft operation rather than a single targeted campaign.
ZDI discloses Linux Kernel QFQ Plus scheduler use-after-free (CVE-2026-22999, CVSS 7.8) enabling local privilege escalation on affected systems.
ZDI advisory ZDI-26-700 covers a use-after-free in the Linux Kernel QFQ Plus scheduler, tracked as CVE-2026-22999 with a CVSS score of 7.8. Exploitation requires the attacker to first execute low-privileged code on the target system. Successful exploitation allows local attackers to escalate privileges. No in-the-wild exploitation is mentioned.
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.
oss-security thread discusses newly disclosed Linux kernel local privilege escalations, including ZcopyReaper (CVE-2026-43502) and about 20 more flaws.
An oss-security mailing list thread discusses newly disclosed Linux kernel local privilege escalation (LPE) issues, headlined by ZcopyReaper (CVE-2026-43502) along with roughly 20 more. Discussants ask whether the many reports could be summarized and note that locking kernel module loading after boot has repeatedly proven an effective mitigation. The visible discussion does not state whether any of the flaws are exploited in the wild or give specific patch guidance beyond the individual reports.
Elastic details a layered detection framework for Linux local privilege escalation, covering 2026's copy-on-write bug wave and LLM-assisted discovery.
Elastic Security Labs describes how most Linux local privilege escalations share a common host flow — an unprivileged process launched from a writable path becoming root — and proposes layered detections combining general outcome-based rules with per-technique rules in Elastic Defend and Auditd. It tracks 13 recent LPE disclosures, seven of which share a copy-on-write/zero-copy bug class, including Copy Fail, DirtyFrag, Fragnesia, DirtyDecrypt, DirtyClone, pedit COW, and RefluXFS. Qualys attributes RefluXFS to an LLM-assisted research effort with Anthropic using Claude Mythos Preview, and another bug is credited to an LLM-assisted workflow. Detection and endpoint rules are published in Elastic's detection-rules and protections-artifacts repositories.
NovaFabric seals autonomous AI agent runs into tamper-evident, replayable Run Capsules enabling third-party audit under EU AI Act and ISO 42001.
NovaFabric records autonomous agent runs without modifying agent logic into portable Run Capsules (fifteen-entity schema) sealed with DSSE signatures, RFC 3161 timestamps, a Merkle log, and redaction attestations, supporting four-mode replay and third-party Evidence Bundle verification. Evaluation shows tampering rejected across three tested classes, 14/14 credential types redacted while preserving 9/9 decoys, and 140/140 mutations localized; blast-radius queries reach 45.5ms p99 over 10M edges. Limits include only 2/10 tool-using workloads completing replay due to missing tool-response substitution and ingest capped at 61.6 req/s. The contribution integrates OpenTelemetry, DSSE/in-toto, and W3C PROV rather than new cryptography.
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.
ZDI discloses CVE-2026-23413, a use-after-free in the Linux kernel net scheduler clsact qdisc allowing local privilege escalation, CVSS 8.2.
ZDI advisory ZDI-26-694 describes a use-after-free vulnerability in the Linux kernel's net scheduler clsact qdisc component. Successful exploitation allows local attackers to escalate privileges on affected installations, and ZDI assigned a CVSS score of 8.2. The flaw is tracked as CVE-2026-23413. The advisory notes an attacker must first obtain the ability to execute high-privileged code on the target system to exploit the vulnerability.
ZDI discloses CVE-2026-64397, a CVSS 9.0 unauthenticated remote code execution race condition in Linux Kernel KSMBD.
ZDI-26-684 describes a race condition in the Linux Kernel KSMBD subsystem's Query Directory Request handling that allows unauthenticated remote attackers to execute arbitrary code. Only systems with KSMBD enabled are vulnerable. ZDI assigned a CVSS rating of 9.0 and CVE-2026-64397.
The Linux kernel net scheduler packet classifier has a use-after-free (CVSS 7.8) allowing local attackers to escalate privileges from low-privileged code.
ZDI-26-609 describes a use-after-free vulnerability in the Linux kernel's network scheduler packet classifier, with a CVSS score of 7.8. An attacker must first be able to execute low-privileged code on the target system before escalating privileges. The advisory text does not list an assigned CVE identifier.
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.
The Linux Foundation adopts TRACE, an OPAQUE-contributed spec giving AI agents hardware-attested, cryptographically verifiable runtime and compliance evidence.
The Linux Foundation accepted the TRACE (Trust, Runtime Attestation and Compliance Evidence) specification contributed by OPAQUE, developed with AMD, Intel, Microsoft, and the Technology Innovation Institute. TRACE binds runtime environment, software, policies, data classifications, and tool usage into a portable, cryptographically verifiable artifact, composing existing standards such as RATS, EAT, SLSA, SCITT, SPIFFE, and EAR. It recorded nearly 135,000 PyPI downloads within 10 weeks of its June 2026 introduction, and its technical workstream will be hosted by the Coalition for Secure AI.
Linux kernel developers discuss a batch of 21 local privilege escalation CVEs, including ZcopyReaper (CVE-2026-43502) in the RDS networking driver.
An oss-security thread examines newly published Linux kernel local privilege escalation issues tracked in the kernel.org security vulnerabilities git repository. CVE-2026-43502, dubbed ZcopyReaper, affects the net/rds (Reliable Datagram Sockets) subsystem. The discussion references roughly 20 additional kernel LPE CVEs published in the 2026 Q3 window.
The Linux Foundation introduced TRACE, an open standard providing hardware-attested runtime and compliance evidence for AI agents.
The Linux Foundation announced TRACE, an open standard designed to generate hardware-attested runtime evidence for AI agents. The standard aims to give auditors and regulators verifiable proof of what AI agents actually executed. It targets compliance and assurance needs for organizations deploying autonomous AI systems.
Infosecurity Magazine covers the XZ Utils open-source backdoor, a malicious implant in liblzma that targeted OpenSSH on major Linux distributions.
The article covers the XZ Utils backdoor, a malicious implant introduced into the widely used open-source compression library. The compromised liblzma code manipulated functions used by OpenSSH, nearly reaching stable releases of major Linux distributions before discovery. The incident is a prominent example of software supply chain compromise targeting critical open-source infrastructure.
ZDI discloses Linux Kernel Open vSwitch use-after-free (CVE-2026-80994) letting low-privileged local attackers disclose sensitive kernel information, CVSS 6.4.
ZDI-26-687 covers a use-after-free information disclosure vulnerability in the Linux Kernel's Open vSwitch flow deletion handling, tracked as CVE-2026-80994 with a CVSS rating of 6.4. Exploitation requires the ability to execute low-privileged code on the target system. The flaw allows local attackers to disclose sensitive information from affected installations.
Zscaler ThreatLabz analyzes Abyssos, a new modular C++ RAT offering credential theft, file exfiltration, and VNC-based remote access.
Zscaler ThreatLabz identified a new malware family tracked as Abyssos in late June 2026. Abyssos is a modular remote administration tool (RAT) written in C++ that supports credential theft, file exfiltration, and remote access via VNC. The malware is under active development, with multiple version numbers and obfuscation passes designed to evade security products. The analysis covers its core features, configuration, obfuscation, and network communication protocol.