From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-68425][MODERATE REGULAR] IB/mad: Drop unmatched RMPP responses before reassembly [ Upstream Date: Mon, 10 Aug 2026 12:37:01 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-68425 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: 4 X-AL-KERNEL-ActionableScore-Lower: 3 X-AL-KERNEL-Commit: dfa535c94406c03d3f0c869ef3ba5528e395737c List-Id: CVE: CVE-2026-68425 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: IB/mad: Drop unmatched RMPP responses before reassembly [ Upstream Commit: dfa535c94406c03d3f0c869ef3ba5528e395737c Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dfa535c94406c03d3f0c869ef3ba5528e395737c Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68425 Analysis date: Mon, 10 Aug 2026 12:37:01 -0400 ActionableScore: 4 ActionableScore lower bound: 3 Actionable bucket: Borderline manual review recommended / Actionable Moderate at minimum Manual review required: YES Summary: Kernel handled IB MAD RMPP DATA responses could enter reassembly before matching an outstanding send, allowing an attacker with access to the RDMA or InfiniBand fabric to create or extend unmatched receive state and potentially cause denial of service. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68425 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68425 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-2026-68425 MODERATE CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-20;**CWE-400;CWE-770;Other CVSS 'AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'Kernel handled IB MAD RMPP DATA responses could enter receive side reassembly before being matched to an outstanding send request. An unsolicited response that reaches a kernel RMPP agent by high TID bits may allocate or extend RMPP receive state before the full TID, management class, and source address are validated. For the CVSS the PR:N is used because the attacker does not need a local account or code execution on the victim, but must be able to send MAD RMPP traffic on the relevant InfiniBand or RDMA fabric. The issue is not Internet remote in the usual sense and is better modeled as AV:A because exploitation requires access to the local fabric or storage cluster network. Impact is primarily denial of service through receive state or memory pressure. No concrete UAF, OOB access, information leak, or write primitive is evident from the patch, so confidentiality and integrity are not raised for this assessment.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended / Actionable Moderate at minimum (with actual score 4) YES OOB LOCK DANGER INIT NETWORK LINUS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 NO NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=4 ActionableScoreLower=3 ## 1. ActionableScore * Conservative score: 3 * Paranoid score: 4 * Final recommended bucket: **Borderline manual review recommended / Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Remote reachable / network-triggerable: +2 The affected path processes incoming IB MAD RMPP responses from the RDMA or InfiniBand fabric. This is not Internet remote, but it is externally triggerable from the relevant local fabric. * Availability impact realistic: +1 Unmatched RMPP DATA responses can allocate or extend receive-side reassembly state before full request matching. This supports a realistic resource/state exhaustion DoS concern. Paranoid additional signal: * Reliable kernel crash / strong DoS: +1 Not directly shown as a panic or UAF, but sustained unsolicited RMPP traffic could plausibly create enough kernel receive state pressure to cause stronger availability impact. Signals not applied: * Generic memory corruption: +0 The patch does not show UAF, OOB access, double free, type confusion, arbitrary write, or stale callback use. * Privilege escalation plausible: +0 No reclaim, overwrite, refcount takeover, callback dispatch, or controlled object confusion is evident. * Confidentiality / integrity impact: +0 The described primitive is pre-validation state allocation or extension, not data disclosure or modification. * Rare subsystem penalty: 0 RDMA/InfiniBand is deployment-specific, but the path is a normal fabric-facing kernel receive path when the subsystem is in use. I would not subtract heavily for rarity. ## 3. Reachability analysis An attacker would need the ability to send crafted MAD/RMPP traffic on the relevant InfiniBand or RDMA management fabric. No local account on the victim is required, so practical CVSS-style PR is PR:N, but the attack is better modeled as adjacent/fabric-reachable rather than Internet-reachable. Namespaces and containers are not the main access boundary here. The meaningful boundary is access to the RDMA/IB fabric and whether kernel-handled RMPP agents are active. This is not a default Internet-exposed path, but it can matter in storage, HPC, and clustered environments. ## 4. Severity interpretation This behaves like an actionable Moderate network-adjacent DoS candidate, not an Important-class memory corruption issue based on the provided patch. The strongest demonstrated issue is that unmatched responses can consume kernel RMPP receive state before full validation. Theoretical impact beyond DoS is not supported by the diff. There is no concrete UAF, overwrite, stale object reuse, information leak, or privilege escalation primitive. Manual review is still recommended because the bug is externally reachable from a fabric network and affects kernel-side receive state before validation. ## 5. One-sentence report phrase Kernel handled IB MAD RMPP DATA responses could enter reassembly before matching an outstanding send, allowing an attacker with access to the RDMA or InfiniBand fabric to create or extend unmatched receive state and potentially cause denial of service. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Reason: network-adjacent kernel receive-state allocation before validation is security-relevant and should not be auto-closed, but the patch does not currently justify Important severity or memory-corruption impact. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: IB/mad: Drop unmatched RMPP responses before reassembly [ Upstream Commit: dfa535c94406c03d3f0c869ef3ba5528e395737c Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=dfa535c94406c03d3f0c869ef3ba5528e395737c Changed files: drivers/infiniband/core/mad.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=dfa535c94406c03d3f0c869ef3ba5528e395737c ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-68425 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68425 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:N/A:L The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 5.3 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: 3 Paranoid ActionableScore: 4 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).