CVE-2023-53867
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: ceph: fix potential use-after-free bug when trimming caps When trimming the caps and just after the 'session->s_cap_lock' is released in ceph_iterate_session_caps() the cap maybe removed by another thread, and when using the stale cap memory in the callbacks it will trigger use-after-free crash. We need to check the existence of the cap just after the 'ci->i_ceph_lock' being acquired. And do nothing if it's already removed.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA race condition in the Linux kernel's Ceph filesystem driver allows a use-after-free vulnerability during cap trimming. When ceph_iterate_session_caps() releases the session->s_cap_lock, another thread can remove a cap, and subsequent use of the stale cap pointer in callbacks triggers the use-after-free. The fix requires checking cap existence after acquiring ci->i_ceph_lock.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Ceph filesystem is in useRun 'lsmod | grep ceph' to check if the ceph kernel module is loaded, and 'mount | grep ceph' to see if any Ceph filesystems are mounted.Affected if The system has the ceph module loaded or a Ceph filesystem mounted, making the vulnerable code path reachable.
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Identify the running kernel versionRun 'uname -r' to get the exact kernel version string.Affected if The kernel version is older than the version containing the CVE-2023-53867 fix; compare against the upstream kernel version that includes the patch.
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Check if the vulnerability fix is present in the sourceExamine the ceph_iterate_session_caps() function in the kernel source code (typically in fs/ceph/caps.c) for the cap existence check that was added after acquiring ci->i_ceph_lock.Affected if The fix (cap existence check after acquiring ci->i_ceph_lock) is absent from the source code, indicating the vulnerability is still present.
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Inspect the session lock handling in the cap trimming codeReview the cap trimming logic in the kernel module for the pattern where the session lock is released but the original thread may still reference the freed cap structure.Affected if The code exhibits the race condition pattern where session lock release allows concurrent cap removal while the original thread continues using the freed memory.
A system is affected if it runs a Linux kernel with Ceph filesystem support (ceph module loaded or mounted) on a kernel version predating the CVE-2023-538367 fix, or where the specific cap existence check after ci->i_ceph_lock acquisition is not present in the source.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply the kernel patch that adds the cap existence check after acquiring ci->i_ceph_lock in ceph_iterate_session_caps(). Systems not using Ceph are not affected.
- Consultation2.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2023-53867 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-53867 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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