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CVE-2026-45955 Linux CVE debrief

A vulnerability in the Linux kernel's md/md-llbitmap subsystem could leave a percpu_ref in a permanently killed state when llbitmap_suspend_timeout() times out. The function returns -ETIMEDOUT without resurrecting the reference, causing subsequent page operations to fail as the page control structure becomes unusable. The fix ensures percpu_ref is resurrected before returning the timeout error, maintaining structural integrity for continued operations.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-06-16
Advisory published
2026-05-27
Advisory updated
2026-06-16

Who should care

Organizations running Linux systems with software RAID (md) configurations using bitmap functionality, particularly those with large RAID arrays where resync operations may experience timeouts. Cloud providers and hosting services utilizing md-raid for storage redundancy should prioritize kernel updates.

Technical summary

The md/md-llbitmap (linked list bitmap) subsystem in the Linux kernel manages bitmap pages for software RAID (md) devices. The llbitmap_suspend_timeout() function waits for a percpu_ref reference count to reach zero before proceeding. If this wait times out, the function previously returned -ETIMEDOUT without calling percpu_ref_resurrect(), leaving the reference in PERCPU_REF_DEAD state. The caller md_llbitmap_daemon_fn() would then continue to the next page without calling llbitmap_resume(), permanently corrupting the page control structure's state. The fix adds percpu_ref_resurrect() before returning the error code, ensuring the structure remains valid for subsequent operations.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel updates containing the fix commits when available from your Linux distribution
  • Monitor vendor security advisories for patched kernel versions
  • If running software RAID (md) with bitmap functionality, prioritize kernel updates on systems where RAID resync operations may be interrupted
  • Review system logs for -ETIMEDOUT errors from md_llbitmap_daemon_fn as potential indicators of this condition

Evidence notes

Vulnerability description sourced from NVD record published 2026-05-27. Fix commits identified in kernel.org stable tree. No CVSS score or severity assigned by NVD at time of disclosure.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45955 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45955

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

  • CVE-2026-45955 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45955

    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/095417d6b669c2dec39a5842ccb94df915f97f54

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb

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

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d

    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.