From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46214][MODERATE 7.0] vsock/virtio: fix accept queue count leak on transport mismatch Date: Thu, 28 May 2026 09:08:46 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46214 X-AL-KERNEL-Priority: MODERATE 7.0 X-AL-KERNEL-Severity: MODERATE 7.0 X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: YES X-AL-KERNEL-ActionableScore: 5 X-AL-KERNEL-ActionableScore-Lower: 4 X-AL-KERNEL-Commit: 65c484726e74013a2ec7ba67a34d87760ae8f390 List-Id: CVE: CVE-2026-46214 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: vsock/virtio: fix accept queue count leak on transport mismatch Commit: 65c484726e74013a2ec7ba67a34d87760ae8f390 Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=65c484726e74013a2ec7ba67a34d87760ae8f390 Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46214 Analysis date: Thu, 28 May 2026 09:08:46 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: NO Summary: A virtio-vsock peer can repeatedly trigger transport mismatch failures that leak accept queue accounting, eventually making the listener reject all new connections and causing a host/guest service DoS. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46214 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46214 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 7.0 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-2026-46214 MODERATE CHECK 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-772;**CWE-400;*CWE-664;Other CVSS 'AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'virtio vsock listener accounting could be corrupted because sk_acceptq_added was called before transport validation and was not undone when vsock_assign_transport failed or selected another transport. A peer with access to the virtio vsock channel can repeat failing connection attempts until sk_ack_backlog appears full, after which the listener rejects new connections. For the CVSS the PR:N is used because the paranoid scenario only requires the ability to send vsock connection attempts from the peer side, not local privileges on the victim. The issue is not Internet reachable but can cross a host guest virtualization boundary where virtio vsock is exposed. Impact is denial of service for the affected listener only, with no supported memory corruption, information disclosure, or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) MAYBE VIRT WARNONLY SIMPLEFIX LEAK ERRORPATH KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=5 ActionableScoreLower=4 ## 1. ActionableScore * Conservative score: 4 * Paranoid score: 5 * Final recommended bucket: **Actionable Moderate at minimum**:: ## 2. Signal breakdown Conservative signals: * Adjacent / virtualization-channel reachable: +2. A peer on the virtio-vsock channel can send connection attempts to the affected listener. * Reliable listener DoS: +1. Repeated transport mismatch failures can permanently increase `sk_ack_backlog` until the listener rejects new connections. * Availability impact realistic: +1. The affected vsock service can become unavailable to new clients. Paranoid additional signal: * Cross-boundary isolation impact: +1. The issue can matter across a host/guest boundary when virtio-vsock is used for host-guest services or agent communication. Limiting factors: * No memory corruption. * No UAF, double free, OOB write, information leak, or privilege escalation primitive. * Not Internet reachable. * Trigger depends on multi-transport mismatch or failure conditions, not ordinary successful connects. ## 3. Reachability analysis The bug can be triggered by a peer that can send virtio-vsock connection attempts to a listening socket. This may be a guest-to-host, host-to-guest, or guest service scenario depending on deployment. No local privileges on the victim are needed for the paranoid peer-triggered scenario, but the attacker must have access to the relevant vsock communication boundary. Containers matter only if vsock access is delegated into the container. The path is not exposed to normal TCP/IP networks. It is relevant mainly for VM environments using virtio-vsock services. ## 4. Severity interpretation This behaves like an actionable Moderate issue. The realistic impact is denial of service for a specific vsock listener by exhausting its logical accept backlog through accounting leakage. It does not behave like an Important memory-corruption vulnerability. The patch supports availability impact only, with no confidentiality, integrity, or LPE evidence. ## 5. One-sentence report phrase A virtio-vsock peer can repeatedly trigger transport mismatch failures that leak accept queue accounting, eventually making the listener reject all new connections and causing a host/guest service DoS. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED Review is recommended for environments exposing important virtio-vsock services across host/guest boundaries, but the issue should remain availability-only unless additional evidence shows memory corruption or privilege escalation. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: vsock/virtio: fix accept queue count leak on transport mismatch Commit: 65c484726e74013a2ec7ba67a34d87760ae8f390 Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=65c484726e74013a2ec7ba67a34d87760ae8f390 Commit description: virtio_transport_recv_listen() calls sk_acceptq_added() before vsock_assign_transport(). If vsock_assign_transport() fails or selects a different transport, the error path returns without calling sk_acceptq_removed(), permanently incrementing sk_ack_backlog. After approximately backlog+1 such failures, sk_acceptq_is_full() returns true, causing the listener to reject all new connections. Fix by moving sk_acceptq_added() to after the transport validation, matching the pattern used by vmci_transport and hyperv_transport. Fixes: c0cfa2d ("vsock: add multi-transports support") Signed-off-by: Dudu Lu Reviewed-by: Bobby Eshleman Reviewed-by: Luigi Leonardi Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20260413131409.19022-1-phx0fer@gmail.com Signed-off-by: Paolo Abeni Cc: Luigi Leonardi Signed-off-by: Greg Kroah-Hartman Changed files: net/vmw_vsock/virtio_transport_common.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=65c484726e74013a2ec7ba67a34d87760ae8f390 ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46214 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46214 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:H/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: 4 Paranoid ActionableScore: 5 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: YES Published priority for this report (same as in Subject): MODERATE 7.0 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).