From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80912][LOW] selinux: reject an unclaimed class value in security_get_classes() Date: Fri, 04 Sep 2026 17:10:34 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80912 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: 0 X-AL-KERNEL-Commit: e0285bb152211c00900136b66d4b420c14a59094 List-Id: CVE: CVE-2026-80912 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: selinux: reject an unclaimed class value in security_get_classes() Commit: e0285bb152211c00900136b66d4b420c14a59094 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e0285bb152211c00900136b66d4b420c14a59094 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80912 Analysis date: Fri, 04 Sep 2026 17:10:34 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A NULL pointer dereference in the SELinux class export path can occur when a sparse policy class table leaves an unclaimed class value that is later passed as a NULL class name to sel_make_dir(), causing local denial of service only. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80912 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80912 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: LOW Manual review required: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-80912 LOW https://www.kernelcve.org/list/?q=CVE-2026-80912 CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;*CWE-20;CWE-754;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the SELinux class export path because security_get_classes sizes the class array by p_classes.nprim but fills entries by class value minus one. A sparse class symbol table can therefore leave a NULL class name which is later passed through sel_make_classes into sel_make_dir and d_alloc_name. For the CVSS the PR:L paranoid case is only defensible if a lower privileged local process can trigger the selinuxfs rebuild or query after a sparse policy is already installed by a privileged actor. The typical practical case is PR:H because loading or replacing SELinux policy is an administrative operation. The issue is not network reachable. Impact is denial of service via kernel oops or crash, with no supported confidentiality or integrity primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES LINUS NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=0 ## 1. ActionableScore * Conservative score: 0 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like** ## 2. Signal breakdown Conservative signals: * Reliable kernel crash / strong DoS: +1. A sparse SELinux class table can leave a NULL entry that later reaches sel_make_dir() and d_alloc_name(), causing a NULL pointer dereference. * Broad/default/common subsystem: +1. SELinux is a common LSM, but this specific path depends on policy export/query behavior. * Requires admin/root/CAP_* in typical deployments: -2. Installing or replacing SELinux policy is normally an administrative operation. * Rare AND difficult-to-reach subsystem/configuration: -1. The issue requires a nonconforming or sparse SELinux policy class layout, not a normal policy. * Effective conservative total is capped at 0 because there is no memory corruption primitive beyond NULL dereference and no unprivileged policy-loading path shown. Paranoid signals: * Reliable kernel crash / strong DoS: +1. Once a sparse policy is present, querying/exporting classes may dereference a NULL class name. * Local unprivileged trigger: +1. This is only defensible if a lower privileged local process can trigger the relevant selinuxfs class query after a malformed policy has already been installed by a privileged actor. * No memory corruption or LPE signal is awarded. The primitive is NULL dereference, not UAF, OOB write, type confusion, refcount misuse, or attacker-controlled object reuse. ## 3. Reachability analysis Typical triggering requires a malformed or sparse SELinux policy to be loaded, which is normally restricted to root or a privileged policy-management service. After such a policy exists, the crash may be reachable through SELinux class export/query paths, but the supplied patch does not prove that an unprivileged user can create the vulnerable policy state. Namespaces and containers do not materially lower the main requirement unless the environment delegates SELinux policy management, which is uncommon. The path is not network reachable. Realistic exploitation is local DoS only and depends on a nonstandard policy state. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like local DoS issue. The patch fixes missing validation of sparse class values before handing class names to later SELinux filesystem creation code. There is no supported confidentiality impact, integrity impact, privilege escalation path, UAF, arbitrary write, or reusable corruption primitive. The paranoid interpretation only raises the score to 2 because a lower privileged local process might be able to trigger the query after a privileged actor installed the bad policy. That still does not make it an Actionable Moderate or Important-class candidate. ## 5. One-sentence report phrase A NULL pointer dereference in the SELinux class export path can occur when a sparse policy class table leaves an unclaimed class value that is later passed as a NULL class name to sel_make_dir(), causing local denial of service only. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED Reason: the issue appears to be a validation bug leading to NULL dereference and local DoS only, with typical PR:H policy-loading requirements and no evidence of memory corruption, privilege escalation, network reachability, or security-boundary bypass. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: selinux: reject an unclaimed class value in security_get_classes() Commit: e0285bb152211c00900136b66d4b420c14a59094 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e0285bb152211c00900136b66d4b420c14a59094 Commit description: security_get_classes() sizes an array by p_classes.nprim and fills it at value - 1, so a class value the policy never defines leaves a NULL. sel_make_classes() passes every entry to sel_make_dir(), reaching the same d_alloc_name() dereference as the permission array. The class symbol table is allowed to be sparse (policydb_class_isvalid() exists to absorb that), but this getter builds its own array straight from the hash table and has no such predicate. Fail the lookup when a value went unclaimed instead of handing out the NULL. Conforming policies define every class they declare and 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/services.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=e0285bb152211c00900136b66d4b420c14a59094 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80912 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80912 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:N/I:N/A:H The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 4.7 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: 0 Paranoid ActionableScore: 2 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: LOW KPANIC detected for this report: NO Published priority for this report (same as in Subject): LOW 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).