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Linux KernelOperating system · Linux

CVE-2026-52957

HIGH · 7.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 5.10.258 / 5.15.209 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click 8 weeks old

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 · unedited
In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential null-ptr-deref in decode_choose_args() A message of type CEPH_MSG_OSD_MAP contains an OSD map that itself contains a CRUSH map. When decoding this CRUSH map in crush_decode(), an array of max_buckets CRUSH buckets is decoded, where some indices may not refer to actual buckets and are therefore set to NULL. The received CRUSH map may optionally contain choose_args that get decoded in decode_choose_args(). When decoding a crush_choose_arg_map, a series of choose_args for different buckets is decoded, with the bucket_index being read from the incoming message. It is only checked that the bucket index does not exceed max_buckets, but not that it doesn't point to an index with a NULL bucket. If a (potentially corrupted) message contains a crush_choose_arg_map including such a bucket_index, a null pointer dereference may occur in the subsequent processing when attempting to access the bucket with the given index. This patch fixes the issue by extending the affected check. Now, it is only attempted to access the bucket if it is not NULL.

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 confidence

Null pointer dereference in libceph's decode_choose_args() when processing CEPH_MSG_OSD_MAP messages containing CRUSH maps. The code validates bucket_index doesn't exceed max_buckets but fails to check if the bucket at that index is NULL. A corrupted message with a bucket_index pointing to a NULL bucket triggers the dereference.

MitigationApply the kernel patch that adds a NULL check for the bucket pointer before attempting to access it in decode_choose_args(). Update to a kernel version containing the fix.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 4.13.1, < 5.10.258>= 5.11, < 5.15.209>= 5.16, < 6.1.175>= 6.2, < 6.6.141>= 6.7, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10= 4.13= 7.1

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the running kernel version
    Run 'uname -r' or 'cat /proc/version' to get the installed kernel version
    Affected if The kernel version falls within the affected ranges: >= 4.13.1, < 5.10.258; >= 5.11, < 5.15.209; >= 5.16, < 6.1.175; >= 6.2, < 6.6.141; >= 6.7, < 6.12.91; >= 6.13, < 6.18.33; >= 6.19, < 7.0.10; = 4.13; = 7.1
  2. Verify libceph kernel module presence
    Run 'lsmod | grep ceph' or check if CONFIG_CEPH_LIB=y or =m in /boot/config-$(uname -r) or /proc/config.gz
    Affected if The libceph or ceph module is loaded (lsmod shows it) or built into the kernel (CONFIG_CEPH_LIB=y or =m)
  3. Check for Ceph client or OSD configuration
    Look for /etc/ceph/ directory, or run 'ceph -s' or check for ceph-related processes (ceph-osd, ceph-mon, ceph-mds)
    Affected if The system has Ceph configuration files, active Ceph processes, or is acting as a Ceph OSD server receiving OSD map messages

You are affected if you are running a vulnerable kernel version from the specified ranges and your system uses libceph functionality (has Ceph OSD clients or is a Ceph OSD server that processes CEPH_MSG_OSD_MAP messages).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 5.10.258 / 5.15.209 / 6.1.175 or later
Fixed in 5.10.2585.15.2096.1.175
Interim mitigation

Apply the kernel patch that adds a NULL check for the bucket pointer before attempting to access it in decode_choose_args(). Update to a kernel version containing the fix.

Recommended fix High confidence

5.10.258 / 5.15.209 / 6.1.175 / 6.6.141 (depending on your current branch)

  1. Identify the currently running kernel version using `uname -r`
  2. Determine which version branch your current kernel belongs to (e.g., 5.10.x, 5.15.x, 6.1.x, 6.2.x)
  3. Upgrade to the fixed version for your branch: for 5.10.x upgrade to >= 5.10.258, for 5.15.x upgrade to >= 5.15.209, for 6.1.x upgrade to >= 6.1.175, or for 6.2+ upgrade to >= 6.6.141
  4. On Debian/Ubuntu: `sudo apt-get update && sudo apt-get upgrade` or install specific kernel package
  5. On RHEL/CentOS: `sudo yum update kernel` or `sudo dnf update kernel`
  6. On Fedora: `sudo dnf update kernel`
  7. Reboot the system to load the new kernel: `sudo reboot`
  8. Verify the fix is applied by checking `uname -r` shows a version >= the fixed version for your branch
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with custom kernel modules or older drivers; test in staging first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52957 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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