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CVE-2026-80527 Linux CVE debrief

A Linux kernel vulnerability (CVE-2026-80527) can cause a reader to hang indefinitely in __ceph_get_caps() due to a stale mds_wanted value. This issue arises when the client no longer holds the FILE_RD capability, but the local cap state still indicates that the capability is wanted. The vulnerability can be triggered through MDS cap revocation. If the cap update requesting FILE_RD never reaches the MDS after cap->mds_wanted was raised, the reader will be left holding only non-file caps while local mds_wanted still includes the file read caps, causing try_get_cap_refs() to return 0 and __ceph_get_caps() to wait indefinitely on i_cap_wq.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-26
Original CVE updated
2026-10-16
Advisory published
2026-08-26
Advisory updated
2026-10-16

Who should care

Linux system administrators and security teams, especially those using ceph, should be aware of this vulnerability and prioritize verifying the patch status of their systems to prevent potential issues. They should also review system logs for signs of cap revocation or hangs and ensure that the fix is applied to prevent potential hangs in __ceph_get_caps().

Why it matters

CVE-2026-80527 is a Linux kernel vulnerability that can cause indefinite hangs in __ceph_get_caps(). Linux system administrators and security teams, especially those using ceph, should prioritize verifying the patch status of their systems to prevent potential issues.

  • Potential indefinite hangs in __ceph_get_caps()
  • Required verification of patch status for Linux systems using ceph
  • Possible impact on system performance or availability

Technical summary

The vulnerability occurs in the __ceph_get_caps() function of the Linux kernel, where a reader can hang indefinitely due to a stale mds_wanted value. This happens when the client no longer holds the FILE_RD capability, but the local cap state still indicates that the capability is wanted. The issue can be triggered through MDS cap revocation. Linux system administrators and security teams should prioritize verifying the patch status of their Linux systems, especially those using ceph, and ensure that the fix is applied to prevent potential hangs in __ceph_get_caps().

Defensive priority

Linux system administrators and security teams should prioritize verifying the patch status of their Linux systems, especially those using ceph, and ensure that the fix is applied to prevent potential hangs in __ceph_get_caps().

Recommended defensive actions

  • Verify patch status of Linux systems using ceph
  • Apply the fix to prevent potential hangs in __ceph_get_caps()
  • Monitor system logs for signs of cap revocation or hangs
  • Review compensating controls for exposed systems
  • Check relevant monitoring, detection, and logs for exposed assets
  • Track exceptions and retest remediated assets
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source item provide details about the vulnerability, its triggers, and potential impact. However, there is limited information on actual exploitation or affected systems. Linux system administrators and security teams should verify patch status and review system logs for signs of cap revocation or hangs. The vulnerability can be triggered through MDS cap revocation, and defenders should focus on verifying patch status and monitoring system performance.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-80527 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-80527

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

  • CVE-2026-80527 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-80527

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

Supplemental references

  • ceph: fix hanging __ceph_get_caps() with stale mds_wanted

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/80xxx/CVE-2026-80527.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/b5661524c5a45085a866864ca9b8ae2513dfd67a

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/5e84bc6f67e19fdd192d8b215de728acbfc12572

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/5fedf279a1ea369d39c8b06dd4547cdc576065d0

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/e05c315b4da0c16ea800ee4b2cb6c617f586d1b5

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/fcce1b3be6d286aa80831e730289f4c062053ae6

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a3bc6b3e9ef3f5f5cb85a902a30a090c7931127c

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9e55fe24c548ad3163903eb58bb002d28d32a630

    Supplemental source

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.