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CVE-2026-52957 Linux CVE debrief

CVE-2026-52957 is a high-severity vulnerability in the Linux kernel's libceph component. The vulnerability occurs in the decode_choose_args() function, where a null-pointer dereference can happen when decoding CRUSH maps. This can be triggered by a potentially corrupted message containing a crush_choose_arg_map with an invalid bucket index. The issue is caused by insufficient checks on the bucket index, which can lead to accessing a NULL bucket. A patch has been applied to extend the affected check, ensuring that the bucket is not NULL before accessing it.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-24
Original CVE updated
2026-07-14
Advisory published
2026-06-24
Advisory updated
2026-07-14

Who should care

Linux kernel users and distributors should be aware of this vulnerability. The vulnerability can be exploited remotely, and its high severity (CVSS score of 7.5) indicates that it could have significant impacts on affected systems. System administrators and security teams should prioritize patching vulnerable systems.

Technical summary

The vulnerability is located in the libceph component of the Linux kernel. Specifically, it affects the decode_choose_args() function, which is responsible for decoding CRUSH maps. A CRUSH map is part of an OSD map message (CEPH_MSG_OSD_MAP). When decoding the CRUSH map, an array of max_buckets CRUSH buckets is created, and some indices may be set to NULL if they do not refer to actual buckets. The function decode_choose_args() decodes choose_args for different buckets. However, it only checks if the bucket index is within the max_buckets limit, not if the bucket is NULL. This oversight allows a potentially corrupted message to cause a null-pointer dereference when accessing the bucket with the given index.

Defensive priority

Apply the patch to update the decode_choose_args() function. Perform a thorough review of system configurations and ensure that all necessary mitigations are in place.

Recommended defensive actions

  • Apply the official patch to update the decode_choose_args() function.
  • Review system configurations to ensure that libceph is properly configured.
  • Perform a thorough vulnerability assessment to identify potential attack vectors.
  • Implement compensating controls, such as monitoring and intrusion detection, to detect potential exploitation attempts.
  • Keep Linux kernel and related packages up-to-date with the latest security patches.

Evidence notes

The CVE record and NVD detail provide information on the vulnerability. The source item URL provides additional context on the vulnerability, including references to the affected code and patch information.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-52957 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-52957

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-52957 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-52957

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/28b0a2ab8c82d0bbdeb8013029c67c978ce6e4bf

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/301286c0ccd37d66b0e40786fd35a4f19cdbd88a

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/312ec973efac0efb9b9ed64214235910e9ecbaa8

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/7169f326a23d0f547fcd90e68b72fd387622e126

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a20e16ebfe2fa65348eb4b2dc7deac330ce03e9c

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d55ffad8d422b5d1cc44dad32bd3d25f4471cd9f

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d7a65a34d2453f8cd3e0cc0e1319740af7e24276

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.