From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-53245][MODERATE REGULAR] net/802/mrp: fix vector attribute parsing in mrp_pdu_parse_vecattr [ Upstream Date: Thu, 25 Jun 2026 09:46:38 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-53245 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: 3 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: ae65714d96f68bb252eb20085320bdaacab36c00 List-Id: CVE: CVE-2026-53245 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: net/802/mrp: fix vector attribute parsing in mrp_pdu_parse_vecattr [ Upstream Commit: ae65714d96f68bb252eb20085320bdaacab36c00 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ae65714d96f68bb252eb20085320bdaacab36c00 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53245 Analysis date: Thu, 25 Jun 2026 09:46:38 -0400 ActionableScore: 3 ActionableScore lower bound: unknown Actionable bucket: Borderline Moderate. Manual review recommended because this is an adjacent-network protocol parser issue, but current evidence does not support memory corruption or privilege escalation Manual review required: YES Summary: A malformed MRP VectorAttribute can cause incorrect event counting and attribute advancement, allowing an adjacent Layer 2 attacker to apply spurious MRP applicant state changes or disrupt subsequent PDU parsing when MRP is enabled. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53245 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53245 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-53245 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L';*CWE-20;CWE-1284;CWE-682;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N';BEST CVSS score: '5.4';DESCR 'A malformed MRP VectorAttribute can be parsed incorrectly because valen is not decremented after the third event in an event byte, valen zero still causes FirstValue consumption, and the attribute value is not advanced correctly across event byte boundaries. An adjacent attacker on the same Layer 2 segment may be able to send crafted MRP PDUs that apply spurious applicant state events or corrupt parsing of following PDU data. For the CVSS the PR:N is used because triggering does not require privileges on the target host, only Layer 2 reachability to an interface where MRP processing is enabled. The issue is adjacent network reachable rather than Internet routable. Impact is mainly protocol state integrity impact and possible local network availability degradation, with no clear evidence of kernel memory corruption or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline Moderate. Manual review recommended because this is an adjacent-network protocol parser issue, but current evidence does not support memory corruption or privilege escalation (with actual score 3) YES SKB LINUS INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ## 1. ActionableScore * Conservative score: 2 * Paranoid score: 3 * Final recommended bucket: **Borderline Moderate. Manual review recommended because this is an adjacent-network protocol parser issue, but current evidence does not support memory corruption or privilege escalation** ## 2. Signal breakdown Triggered signals: * Remote reachable / network-triggerable: +2 Crafted MRP PDUs can be sent from the same Layer 2 segment to an interface where MRP processing is enabled. This is adjacent-network reachable, not Internet-routable. * Integrity impact plausible: +1 The parser can apply a spurious MRP applicant event or apply events to the wrong attribute value, corrupting protocol state. * Availability impact realistic: +1 in paranoid score only Incorrect MRP state or corrupted parsing of subsequent PDU data may degrade registration behavior on the local L2 domain, but the patch does not show a reliable kernel crash. Subtracted signals: * Rare AND difficult-to-reach subsystem/configuration: -1 MRP is not a common default-exposed Internet-facing path. Practical exposure depends on MRP being enabled and reachable on the local Layer 2 segment. Not triggered: * No generic memory corruption. The patch shows parser state and protocol-state correction, not UAF, OOB write, double free, type confusion, or arbitrary write. * No privilege escalation plausible. No reclaim primitive, write primitive, callback corruption, or object lifetime misuse is shown. * No reliable kernel crash / strong DoS. The commit describes spurious events and offset corruption for later parsing, not panic, Oops, BUG, or host-wide crash. ## 3. Reachability analysis An attacker would need Layer 2 adjacency and the ability to send crafted MRP frames to a target interface where MRP is active. No local account on the target is required, so PR is effectively none for the network-adjacent case. This is not remotely reachable across normal IP routing and is unlikely to be exposed to the public Internet. Namespaces and containers do not materially lower the requirement unless the attacker already has access to inject raw L2 traffic on the relevant network segment. The path is configuration-dependent and protocol-specific, so exposure is narrower than core TCP/IP or netfilter packet paths. ## 4. Severity interpretation This behaves like a borderline Moderate network-adjacent parser bug. The realistic impact is protocol-state integrity corruption and possible local network availability degradation. Theoretical escalation beyond that is not supported by the patch because there is no demonstrated memory-corruption primitive, stale pointer, OOB write, or attacker-controlled overwrite. ## 5. One-sentence report phrase A malformed MRP VectorAttribute can cause incorrect event counting and attribute advancement, allowing an adjacent Layer 2 attacker to apply spurious MRP applicant state changes or disrupt subsequent PDU parsing when MRP is enabled. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: this is network-adjacent parser logic in a kernel networking protocol, so it should not be blindly auto-closed, but current evidence supports protocol-state corruption rather than kernel memory corruption or privilege escalation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: net/802/mrp: fix vector attribute parsing in mrp_pdu_parse_vecattr [ Upstream Commit: ae65714d96f68bb252eb20085320bdaacab36c00 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ae65714d96f68bb252eb20085320bdaacab36c00 Changed files: net/802/mrp.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=ae65714d96f68bb252eb20085320bdaacab36c00 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-53245 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53245 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:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N The Best / paranoid CVSS vector: AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L The Best / paranoid CVSS score: 5.4 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: 3 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).