From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-64111][MODERATE 7.0] lsm: hold cred_guard_mutex for lsm_set_self_attr() Date: Sun, 19 Jul 2026 23:00:26 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-64111 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 6 X-AL-KERNEL-ActionableScore-Lower: 5 X-AL-KERNEL-Commit: 82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 List-Id: CVE: CVE-2026-64111 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: lsm: hold cred_guard_mutex for lsm_set_self_attr() Commit: 82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64111 Analysis date: Sun, 19 Jul 2026 23:00:26 -0400 ActionableScore: 6 ActionableScore lower bound: 5 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64111 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64111 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE 7.0 Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-64111 MODERATE CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N';CWE-362;CWE-367;CWE-284;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N';BEST CVSS score: '6.3';DESCR 'lsm_set_self_attr could call security_setselfattr without holding cred_guard_mutex, unlike the existing procfs attribute write path. For SELinux and AppArmor this matters because the hook may check whether the task is being ptraced before allowing a label or profile transition. A local attacker able to run code and use the self attribute interface could race ptrace state against the transition check, potentially bypassing LSM ptrace based restrictions. For the CVSS the PR:L is used because reliable triggering requires a local process context but not full administrator privileges. The issue is not network reachable. Impact is mainly confidentiality and integrity policy bypass, and the paranoid interpretation treats it as possible local privilege or confinement escape within the LSM policy boundary.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 6) YES WRITE OOB LOCK SIMPLEFIX LINUS KPANIC KPANIC LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=6 ActionableScoreLower=5 1. ActionableScore * Conservative score: 5 * Paranoid score: 6 * Final recommended bucket: **Actionable Moderate at minimum**:: 2. Signal breakdown * Local unprivileged trigger: +1. The affected path is a syscall for setting self LSM attributes and can be reached by a local process context. * Security-boundary bypass with practical sensitive-object access: +2. The missing `cred_guard_mutex` can race SELinux/AppArmor ptrace checks during label or profile transition decisions. * Cross-boundary isolation/policy bypass: +1. The bug affects MAC policy enforcement and ptrace-related transition authorization. * Confidentiality impact plausible: +1. A ptrace policy bypass can expose process state that should be protected by LSM policy. * Integrity impact plausible: +1. A transition allowed under an inconsistent ptrace state may let a process enter or affect a security context that policy intended to restrict. * Hard or unreliable race / special timing required: -1. The issue depends on a race between ptrace state and LSM self-attribute transition handling. * No generic memory corruption: +0. The patch does not show UAF, OOB access, double free, refcount misuse, or attacker-controlled kernel memory corruption. 3. Reachability analysis A local process can potentially trigger the vulnerable syscall path if `lsm_set_self_attr()` is available and SELinux or AppArmor implements relevant transition checks. The issue is not network reachable. It does not require full host root in the meaningful security-boundary sense, because the concern is bypassing LSM or ptrace-mediated restrictions rather than using already equivalent privileges. Containers or reduced-capability service contexts may matter if they rely on SELinux/AppArmor confinement and can reach the syscall, so PR:L is the practical interpretation. The path is relevant mainly on systems using SELinux or AppArmor with policies where ptrace relationships affect transition authorization. 4. Severity interpretation This behaves like an actionable Moderate security-boundary race, not an ordinary low-risk cleanup and not a memory-corruption Important by itself. The realistic impact is a local SELinux/AppArmor policy or ptrace authorization bypass affecting confidentiality and integrity within the MAC policy model. Theoretical privilege or confinement escape is plausible enough for manual review, but the patch does not demonstrate a concrete arbitrary write, UAF reclaim, or code execution primitive. 5. One-sentence report phrase `lsm_set_self_attr() missed cred_guard_mutex serialization before calling the LSM setselfattr hook, allowing a local race against SELinux or AppArmor ptrace transition checks and creating a plausible confidentiality and integrity policy bypass.` 6. Manual review recommendation MANUAL CHECK REQUIRED. This is a race in an LSM authorization path with plausible SELinux/AppArmor policy bypass impact, even though it is not memory corruption and is not remotely reachable. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: lsm: hold cred_guard_mutex for lsm_set_self_attr() Commit: 82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 Commit description: Just as proc_pid_attr_write() already does before calling the LSM hook. This only matters for SELinux and AppArmor which check whether the process is being ptraced and if so, whether to allow the transition. Cc: stable@vger.kernel.org Signed-off-by: Stephen Smalley Acked-by: Casey Schaufler Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman Changed files: security/lsm_syscalls.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=82d3acee88593e3d9e71cad4b7d6b3cf70de9d07 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-64111 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64111 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N The Best / paranoid CVSS score: 6.3 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: 5 Paranoid ActionableScore: 6 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: YES Published priority for this report (same as in Subject): MODERATE 7.0 These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).