From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-90327][MODERATE REGULAR] phonet: pep: do not write beyond optlen in getsockopt [ Upstream Date: Thu, 17 Sep 2026 16:42:48 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-90327 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 1 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: 6054fed6bad08b6d03973e8ffca7f0c9394d1c30 List-Id: CVE: CVE-2026-90327 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: phonet: pep: do not write beyond optlen in getsockopt [ Upstream Commit: 6054fed6bad08b6d03973e8ffca7f0c9394d1c30 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6054fed6bad08b6d03973e8ffca7f0c9394d1c30 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90327 Analysis date: Thu, 17 Sep 2026 16:42:48 -0400 ActionableScore: 1 ActionableScore lower bound: unknown Actionable bucket: Ordinary Moderate Manual review required: NO Summary: No one-sentence report phrase was found. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90327 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90327 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 REGULAR 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-2026-90327 MODERATE https://www.kernelcve.org/list/?q=CVE-2026-90327 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L';*CWE-787;CWE-805;CWE-130;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '4.4';DESCR 'pep_getsockopt can write one to three bytes beyond the caller supplied logical buffer because the reported length is clamped to optlen while put_user still stores a full integer. The overwrite affects userspace memory belonging to the calling process and does not directly corrupt kernel memory. For the CVSS the PR:L value is used because a local user or process must create or access a Phonet PEP socket and invoke getsockopt with a short optlen. The issue is not directly network reachable because the vulnerable operation is a local syscall rather than packet processing. Impact is primarily limited integrity loss in the calling application and possibly an application crash. No direct kernel privilege escalation primitive is established by the affected code.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) SKIP CVE-2026-90327 UNKNOWN SKIP No affected files built, so skip this CVE NO - - unknown MAYBE DANGER SIMPLEFIX DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=1 PrimitiveClass=CLASS_C RealUAF=NO HostAdminRequired=NO NamespaceScopedPrivilege=NO ImportantCandidate=NO ManualReview=NO AutoDowngradeAllowed=YES 1. ActionableScore * Raw conservative score: 1 * Conservative score: 1 * Raw paranoid score: 1 * Paranoid score: 1 * No floor or cap was applied. * Final recommended bucket: **Ordinary Moderate**:: 2. Signal breakdown * +1 Local unprivileged trigger. A process holding a Phonet PEP socket can invoke `getsockopt()` with an `optlen` smaller than `sizeof(int)`. * No kernel-corruption point. The four-byte `put_user()` writes only to a user-supplied userspace address that is validated as writable. * No reliable kernel crash point. The demonstrated effect is limited to one to three bytes beyond the caller-declared userspace buffer. * No integrity point. Unauthorized modification of another principal, protected kernel state, or privileged application state is not established. * No confidentiality point. No data is disclosed outside the calling process. * No remote-reachability point. The vulnerable operation is a local syscall, not Phonet packet processing. * No UAF, refcount mutation, controlled reclaim, arbitrary kernel write, authorization bypass, or privilege-escalation primitive is established. * The previous LLM manual-check recommendation is not supported by an unresolved kernel-security primitive. 3. Reachability analysis The direct trigger is a local process invoking `getsockopt()` on a Phonet PEP socket while supplying a short output length. The caller controls both the destination pointer and the length, and the resulting overwrite remains in that caller's writable userspace memory. No host-admin-equivalent operation is needed for the vulnerable `getsockopt()` call itself. No namespace capability or prior privileged setup is shown as part of the relevant operation. The issue is deterministic and does not require a race, special timing, or remote traffic. Kernel support for Phonet and access to a suitable socket are prerequisites, but subsystem specialization alone does not justify a score reduction. 4. Primitive and severity interpretation The exact primitive is a bounded one-to-three-byte overwrite beyond a caller-declared userspace buffer. It is not a kernel-buffer OOB write because `put_user()` targets userspace and verifies that the complete integer destination is writable. The demonstrated consequence is corruption of adjacent memory in the calling process, potentially causing that process to malfunction or terminate. A security effect involving a privileged application would require an additional, unestablished interface through which an attacker could control that application's buffer placement and `optlen`. This is therefore CLASS_C rather than CLASS_A or CLASS_B. There is no real UAF, kernel lifetime violation, kernel memory corruption, or security-boundary bypass. ImportantCandidate is NO and AutoDowngradeAllowed is YES because no unresolved kernel exploitation primitive remains. 5. One-sentence report phrase `pep_getsockopt()` could write one to three bytes beyond a caller-declared userspace buffer, but the overwrite remains within caller-writable userspace and does not establish kernel corruption, privilege escalation, or remote reachability. 6. Manual review recommendation NO MANUAL CHECK NEEDED The issue is a tightly bounded self-directed userspace overwrite with no demonstrated kernel-security or cross-principal consequence. 7. Call-site confidence Call-site confidence: medium ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: phonet: pep: do not write beyond optlen in getsockopt [ Upstream Commit: 6054fed6bad08b6d03973e8ffca7f0c9394d1c30 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6054fed6bad08b6d03973e8ffca7f0c9394d1c30 Changed files: net/phonet/pep.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=6054fed6bad08b6d03973e8ffca7f0c9394d1c30 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-90327 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90327 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:L/UI:N/S:U/C:N/I:L/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L The Best / paranoid CVSS score: 4.4 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: unknown Paranoid ActionableScore: 1 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: NO Published priority for this report (same as in Subject): MODERATE REGULAR 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).