From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-80784][LOW] mptcp: pm: fix memory leak from alloc-during-teardown race [ Upstream Date: Fri, 04 Sep 2026 18:23:32 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-80784 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: f48341830e4202db3fe884b819b2db6740f0537d List-Id: CVE: CVE-2026-80784 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: mptcp: pm: fix memory leak from alloc-during-teardown race [ Upstream Commit: f48341830e4202db3fe884b819b2db6740f0537d Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f48341830e4202db3fe884b819b2db6740f0537d Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80784 Analysis date: Fri, 04 Sep 2026 18:23:32 -0400 ActionableScore: 2 ActionableScore lower bound: 0 Actionable bucket: Ordinary Moderate / Low-like Manual review required: YES Summary: A race between MPTCP userspace PM ANNOUNCE handling and socket teardown can leak PM list entries under sustained concurrent ANNOUNCE and close activity, causing possible local resource exhaustion without evidence of memory corruption or privilege escalation. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80784 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80784 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-80784 LOW https://www.kernelcve.org/list/?q=CVE-2026-80784 CHECK WITH IMPACT FROM ORIG NN IMPORTANT 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-401;CWE-362;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'MPTCP userspace PM has an alloc during teardown race where a concurrent ANNOUNCE operation can add entries to pm lists after mptcp_pm_destroy has already emptied them for the same msk. This leaks mptcp_pm_add_addr and mptcp_pm_addr_entry objects under sustained ANNOUNCE and close load and can eventually cause memory pressure or resource exhaustion. For the CVSS the PR:L is used for the paranoid score because CAP_NET_ADMIN or delegated net admin control may be available to a reduced capability local actor in containers or service contexts, even though a typical host setup may treat it as PR:H. The issue is not directly network reachable and requires local control of the MPTCP userspace PM generic netlink path. Impact is denial of service via memory exhaustion, with no evidence of UAF, OOB access, information disclosure, or privilege escalation from the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1) YES REMOTE OOB LOCK INIT RACE LEAK NETWORK LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES 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: * Availability impact realistic: +1. Sustained concurrent ANNOUNCE plus close activity can leak kernel memory and may eventually cause memory pressure. * Hard or unreliable race / special timing required: -1. The leak requires an alloc-during-teardown interleaving on the same MPTCP socket. * Requires CAP_NET_ADMIN in typical deployments: -2. The userspace PM generic netlink ANNOUNCE path is normally an administrative MPTCP path. Conservative total is floored at 0. Paranoid signals: * Local reduced-privilege trigger concern: +1. In container, namespace, or service-account deployments, delegated network administration may make this reachable by a non-full-root actor. * Availability impact realistic: +1. Repeated triggering can create persistent memory leaks and resource exhaustion. * Hard race / interleaving required: -1. The race still requires concurrency between userspace PM ANNOUNCE and socket teardown. * Reduced privilege penalty not applied fully: +1 effective adjustment. CAP_NET_ADMIN may be delegated and should not always be treated as equivalent to full host root. Paranoid total: 2. No points awarded for memory corruption, UAF, OOB access, information disclosure, integrity impact, privilege escalation, remote reachability, or security-boundary bypass. The patch and commit describe leaked list entries, not stale object reuse or attacker-controlled memory corruption. ## 3. Reachability analysis The bug is reachable through the MPTCP userspace path manager generic netlink ANNOUNCE operation racing with teardown of the same MPTCP socket. In ordinary host deployments this normally requires CAP_NET_ADMIN or equivalent control over MPTCP PM configuration, so it is not a plain unprivileged local attack. Namespace and container setups can lower practical privilege requirements if CAP_NET_ADMIN is delegated to a container root or service account, but the issue remains local control-plane reachable rather than network-triggerable by packet traffic. The affected path is specific to MPTCP userspace PM and requires sustained concurrent ANNOUNCE plus close activity, so exposure is narrower than core TCP or common packet receive paths. Call-site confidence: high. The supplied patch includes both allocation paths and the teardown path. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource exhaustion issue, not an Important-class vulnerability. The realistic impact is memory leak accumulation and possible DoS under sustained local administrative or delegated network-management activity. There is no supported evidence of UAF exploitation, object replacement, write-after-free, type confusion, information disclosure, or privilege escalation. The paranoid score accounts for delegated CAP_NET_ADMIN environments, but it should still not be treated as Actionable Moderate unless product policy treats MPTCP userspace PM access as available to untrusted tenants. ## 5. One-sentence report phrase A race between MPTCP userspace PM ANNOUNCE handling and socket teardown can leak PM list entries under sustained concurrent ANNOUNCE and close activity, causing possible local resource exhaustion without evidence of memory corruption or privilege escalation. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED. Reason: this is a constrained memory leak / resource exhaustion race, gated by local MPTCP userspace PM control in typical deployments, with no demonstrated memory-corruption or security-boundary-bypass primitive. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: mptcp: pm: fix memory leak from alloc-during-teardown race [ Upstream Commit: f48341830e4202db3fe884b819b2db6740f0537d Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f48341830e4202db3fe884b819b2db6740f0537d Changed files: net/mptcp/pm_netlink.c net/mptcp/pm_userspace.c net/mptcp/protocol.c net/mptcp/protocol.h 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=f48341830e4202db3fe884b819b2db6740f0537d ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-80784 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80784 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:H/PR:H/UI:N/S:U/C:N/I:N/A:L 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).