From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-46012][MODERATE 7.0] rxrpc: Fix memory leaks in rxkad_verify_response() Date: Wed, 27 May 2026 12:32:08 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-46012 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: c4b8f32e73eafd4a5076be890c7c8506ec04567c List-Id: CVE: CVE-2026-46012 Priority: MODERATE 7.0 AL-KERNEL base severity: MODERATE KPANIC flag: YES Patch: rxrpc: Fix memory leaks in rxkad_verify_response() Commit: c4b8f32e73eafd4a5076be890c7c8506ec04567c Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4b8f32e73eafd4a5076be890c7c8506ec04567c Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46012 Analysis date: Wed, 27 May 2026 12:32:08 -0400 ActionableScore: 5 ActionableScore lower bound: 4 Actionable bucket: Actionable Moderate at minimum Manual review required: YES Summary: Malformed RxRPC rxkad RESPONSE packets can drive error paths that leak ticket buffers and server key references, enabling remote DoS through resource exhaustion on reachable RxRPC services. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46012 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46012 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: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-46012 MODERATE CHECK Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H';*CWE-401;*CWE-772;**CWE-400;Other CVSS 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '7.5';DESCR 'RxRPC rxkad_verify_response() could leak the Kerberos ticket buffer and server key reference when malformed or failing RESPONSE packets follow error paths before common cleanup. A remote peer can potentially trigger these paths by sending invalid RXRPC RESPONSE traffic when an RxRPC or AFS style service is reachable. For the CVSS the PR:N is used because no local privileges are needed once the service is exposed to the peer. Impact is denial of service through memory or key reference exhaustion only. The issue does not involve UAF, out of bounds write, arbitrary write, information disclosure, or privilege escalation.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 5) YES INIT NOMEMCHK LEAK SKB LINUS PACKET KPANIC INCREASED_TO_MODERATE_FROM_LOW_BASED_ON_GUESSCVSS YES NO 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: * Remote reachable / network-triggerable: +2 A remote RxRPC peer can send malformed or failing RESPONSE packets when an RxRPC or AFS-style service is exposed. * Availability impact realistic: +1 Leaked ticket buffers and server key references can accumulate and cause memory or reference exhaustion. * Network protocol parser / authentication path: +1 The issue is in RxRPC rxkad secure connection verification. Paranoid additional signal: * Sustained remote resource exhaustion concern: +1 If malformed RESPONSE packets can be sent repeatedly, exhaustion may become stronger than a single low-impact leak. No signals apply for UAF, OOB write, arbitrary write, information disclosure, privilege escalation, or direct kernel memory corruption. ## 3. Reachability analysis The issue is reachable only on systems using RxRPC security, such as AFS/RxRPC deployments. A remote peer can influence the RESPONSE processing path by sending malformed or failing packets. Namespaces and containers are not central. Practical risk depends on whether RxRPC services are enabled and reachable by untrusted peers, and whether repeated failed responses can be generated at scale. ## 4. Severity interpretation This is an Actionable Moderate network resource-exhaustion issue. It is not an Important memory-corruption issue based on the patch. The realistic impact is DoS through memory or key reference leaks. The patch does not indicate UAF, OOB write, arbitrary write, data disclosure, or privilege escalation. ## 5. One-sentence report phrase Malformed RxRPC rxkad RESPONSE packets can drive error paths that leak ticket buffers and server key references, enabling remote DoS through resource exhaustion on reachable RxRPC services. ## 6. Manual review recommendation MANUAL CHECK REQUIRED Reason: this is a potentially network-reachable resource leak in an RxRPC authentication path. Manual review should confirm service exposure and whether repeated malformed responses can exhaust resources in practice. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: rxrpc: Fix memory leaks in rxkad_verify_response() Commit: c4b8f32e73eafd4a5076be890c7c8506ec04567c Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c4b8f32e73eafd4a5076be890c7c8506ec04567c Commit description: Fix rxkad_verify_response() to free the ticket and the server key under all circumstances by initialising the ticket pointer to NULL and then making all paths through the function after the first allocation has been done go through a single common epilogue that just releases everything - where all the releases skip on a NULL pointer. Fixes: 57af281 ("rxrpc: Tidy up abort generation infrastructure") Fixes: ec832bd ("rxrpc: Don't retain the server key in the connection") Closes: https://sashiko.dev/#/patchset/20260408121252.2249051-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Jeffrey Altman cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260422161438.2593376-2-dhowells@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman Changed files: net/rxrpc/rxkad.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=c4b8f32e73eafd4a5076be890c7c8506ec04567c ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-46012 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46012 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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L The Best / paranoid CVSS vector: AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H The Best / paranoid CVSS score: 7.5 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).