From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80757][MODERATE 7.0] selinux: reject a class permission count below its inherited common Date: Thu, 03 Sep 2026 05:14:57 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80757 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: 8 X-AL-KERNEL-ActionableScore-Lower: 5 X-AL-KERNEL-Commit: 2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 List-Id: CVE: CVE-2026-80757 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: selinux: reject a class permission count below its inherited common Commit: 2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80757 Analysis date: Thu, 03 Sep 2026 05:14:57 -0400 ActionableScore: 8 ActionableScore lower bound: 5 Actionable bucket: Strong Important candidate / Actionable Moderate at minimum Manual review required: YES Summary: A malformed SELinux policy can declare a class permission count smaller than its inherited common permission count, causing security_get_permissions() to write past a class sized heap array during policy loading and creating a local kernel memory corruption risk. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80757 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80757 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-2026-80757 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-80757 CHECK WITH IMPACT FROM ORIG NN IMPORTANT Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H';*CWE-787;CWE-122;*CWE-20;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H';BEST CVSS score: '7.8';DESCR 'A malformed SELinux policy can define a class that inherits a common permission set while declaring fewer permissions than that common. During policy loading, security_get_permissions() can then map common permissions into an array sized by the smaller class permission count, causing an out of bounds heap write in kernel memory. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate SELinux policy loading to a confined policy management process or reduced capability administrator, although typical systems require high privileges to load SELinux policy. The issue is not network reachable and requires local ability to supply or load a policy image. Impact is at least local denial of service via kernel memory corruption and in worst case may allow confidentiality, integrity, and availability impact due to the OOB heap write primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7) YES WRITE OOB SIMPLEFIX IMPROVEONLY LINUS KPANIC DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=8 ActionableScoreLower=5 ## 1. ActionableScore * Conservative score: 5 * Paranoid score: 8 * Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Memory corruption, Strong corruption primitive: +2. The commit explicitly states an out of bounds heap write during SELinux policy load. * Weak LPE concern: +1. Kernel heap corruption can theoretically affect security sensitive state, but the patch does not show controlled target selection, reclaim, or an arbitrary write primitive. * Reliable kernel crash / strong DoS: +1. An OOB heap write during policy parsing can realistically crash or corrupt the kernel. * Integrity impact plausible: +1. The corrupted object is in SELinux policy/security state or adjacent heap memory. * Broad/security sensitive subsystem: +1. SELinux policydb is a core LSM policy subsystem on many enterprise systems. * Requires admin/root/CAP in typical deployments: -2. Loading SELinux policy normally requires highly privileged local access. Paranoid additions / changes: * Privilege escalation plausible: +2 instead of weak +1. A malformed policy image provides attacker influenced parser input and reaches a kernel heap OOB write in a security critical subsystem. * Confidentiality impact plausible: +1. Kernel heap corruption can plausibly affect sensitive kernel or LSM state. * No full admin penalty in the paranoid model. Some environments may delegate policy loading to a reduced capability policy management process or service account, so this is not always equivalent to full host root. ## 3. Reachability analysis The bug is local and requires the ability to supply and load a malformed SELinux policy image. It is not network reachable by itself. In typical deployments, SELinux policy loading is restricted to root or a highly privileged policy management path, so the conservative interpretation applies an admin privilege penalty. Namespaces and containers usually do not make SELinux policy loading available to ordinary container users, but delegated policy management or reduced capability service accounts can make PR:L a defensible paranoid interpretation. The vulnerable path is not a packet parser or default remote interface. However, SELinux is a broadly deployed security subsystem, and the bug is in policy parsing for a privileged kernel security object. Realistic exploitation depends on whether an attacker can influence a policy image accepted by the system. ## 4. Severity interpretation This is not an ordinary Moderate validation bug. The patch prevents a concrete out of bounds heap write, not just a warning or malformed metadata rejection. Realistic exploitation for LPE is not demonstrated because there is no shown arbitrary write target, heap shaping, or reclaim primitive. Still, kernel heap corruption in SELinux policy loading is sufficiently serious to require manual review and should be treated as at least Actionable Moderate, with a Strong Important candidate paranoid bucket. ## 5. One-sentence report phrase A malformed SELinux policy can declare a class permission count smaller than its inherited common permission count, causing security_get_permissions() to write past a class sized heap array during policy loading and creating a local kernel memory corruption risk. ## 6. Manual review recommendation MANUAL CHECK REQUIRED. YES REQUIRES MANUAL CHECK. Reason: the patch fixes an explicitly described OOB heap write in kernel memory inside SELinux policy parsing, with plausible DoS and potential privilege escalation concerns despite privileged reachability in typical deployments. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: selinux: reject a class permission count below its inherited common Commit: 2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 Commit description: security_get_permissions() maps an inherited common's permissions into an array sized by the class's own permissions.nprim, but class_read() takes that nprim verbatim from the policy image and never checks that it covers the common. A class that inherits a common of N permissions while declaring a smaller nprim is accepted, and on load the common's permissions are written past the class-sized array -- an out-of-bounds heap write. Reject a class whose permission count is below its inherited common's. Well-formed policies, where the class count already includes the inherited permissions, are unaffected. Cc: stable@vger.kernel.org Fixes: 55fcf09 ("selinux: add support for querying object classes and permissions from the running policy") Signed-off-by: Bryam Vargas Acked-by: Stephen Smalley Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman Changed files: security/selinux/ss/policydb.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=2002ff745db64ac83ee1bb9ff78196d2d68bfdb3 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80757 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80757 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:L/PR:H/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H The Best / paranoid CVSS score: 7.8 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: 8 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).