From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-52962][LOW] ceph: fix a buffer leak in __ceph_setxattr() Date: Fri, 26 Jun 2026 11:02:06 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-52962 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: 1 X-AL-KERNEL-Commit: 521e5aba857fd267624892c8dd6295f22ce0267e List-Id: CVE: CVE-2026-52962 Priority: LOW AL-KERNEL base severity: LOW KPANIC flag: NO Patch: ceph: fix a buffer leak in __ceph_setxattr() Commit: 521e5aba857fd267624892c8dd6295f22ce0267e Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=521e5aba857fd267624892c8dd6295f22ce0267e Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52962 Analysis date: Fri, 26 Jun 2026 11:02:06 -0400 ActionableScore: 2 ActionableScore lower bound: 1 Actionable bucket: Ordinary Moderate / Low-like Manual review required: NO Summary: A missing `ceph_buffer_put()` in the CephFS `__ceph_setxattr()` retry path can leak buffer references and may allow a local user with CephFS xattr access to cause gradual kernel memory exhaustion. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52962 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52962 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: NO A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-52962 LOW CHECK 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-772;**CWE-400;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'A buffer leak in CephFS __ceph_setxattr() can occur when old_blob stores a preallocated xattr blob during a retry path but the reference is not released before the sync path continues. A local process with access to a mounted CephFS filesystem and permission to set xattrs could repeatedly trigger the affected path and consume kernel memory over time. For the CVSS the PR:L is used because the attacker needs local code execution and filesystem access, but not full administrative privileges. The issue is not directly network reachable from a remote host because it is triggered through local VFS xattr operations on the client. Impact is denial of service through resource exhaustion. There is no supported evidence of UAF, OOB access, information disclosure, or privilege escalation from this patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) MAYBE DISK SIMPLEFIX LEAK LINUS - - checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=2 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 2 * Final recommended bucket: **Ordinary Moderate / Low-like**:: ## 2. Signal breakdown Conservative signals: * Local unprivileged trigger: +1. A local process with access to a mounted CephFS filesystem and permission to set xattrs may reach `__ceph_setxattr()`. * Hard or unreliable retry path: -1. The leak is tied to a retry path involving `old_blob` and `prealloc_blob`, not every normal xattr operation. * Availability impact realistic: +1. Repeated triggering may consume kernel memory over time. Paranoid additional interpretation: * Reliable kernel crash / strong DoS: +1. Only in the sustained-abuse case where repeated leaks realistically exhaust memory. * No memory corruption score. The patch fixes a missing `ceph_buffer_put()` reference drop, not UAF, double-free, OOB write, or object confusion. * No C/I score. There is no evidence of information disclosure, integrity corruption, privilege escalation, or sensitive-object access. ## 3. Reachability analysis The bug is locally reachable through CephFS xattr operations on a client with a mounted CephFS filesystem. The attacker needs local execution plus permission to set extended attributes on affected files or directories. It is not directly network-triggerable by a remote host because the vulnerable path is a local VFS/CephFS client operation, not Ceph network packet parsing. Containers or delegated mounts may make the local trigger easier, but this still remains PR:L rather than PR:N. CephFS is not a default path on most systems, and the vulnerable leak appears retry-dependent. ## 4. Severity interpretation This behaves like an ordinary Moderate or Low-like resource leak, not an Important-class kernel vulnerability. The theoretical impact is local memory exhaustion and DoS after repeated triggering. There is no realistic evidence in the patch of memory corruption, UAF reclaim, controlled overwrite, page-cache corruption, privilege escalation, or cross-boundary security bypass. ## 5. One-sentence report phrase A missing `ceph_buffer_put()` in the CephFS `__ceph_setxattr()` retry path can leak buffer references and may allow a local user with CephFS xattr access to cause gradual kernel memory exhaustion. ## 6. Manual review recommendation NO MANUAL CHECK NEEDED This is a local resource leak without evidence of memory corruption, privilege escalation, network reachability, or sensitive-object access. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: ceph: fix a buffer leak in __ceph_setxattr() Commit: 521e5aba857fd267624892c8dd6295f22ce0267e Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=521e5aba857fd267624892c8dd6295f22ce0267e Commit description: The old_blob in __ceph_setxattr() can store ci->i_xattrs.prealloc_blob value during the retry. However, it is never called the ceph_buffer_put() for the old_blob object. This patch fixes the issue of the buffer leak. Cc: stable@vger.kernel.org Signed-off-by: Viacheslav Dubeyko Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman Changed files: fs/ceph/xattr.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=521e5aba857fd267624892c8dd6295f22ce0267e ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-52962 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52962 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:L/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: 1 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).