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CVE-2026-89649

Critical Vulnerability: CVE-2026-89649

In the Linux kernel, the following vulnerability has been resolved: ceph: bound xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len"

Monday, September 14, 2026Vulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-89649 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Executive Summary

In the Linux kernel, the following vulnerability has been resolved:

ceph: bound xattr value length in __build_xattrs()

__build_xattrs() decodes the MDS-supplied xattr blob one attribute at a

time. For each attribute it reads a 32-bit name length, advances past the

name bytes, reads a 32-bit value length, records the value pointer, and

advances past the value bytes. The two length fields are read with

ceph_decode_32_safe(), but the value bytes themselves are advanced over

with a bare "p += len" and no ceph_decode_need() check that "len" bytes

remain in the blob.

For every attribute except the last, the next iteration's

ceph_decode_32_safe() on the following name length implicitly verifies

that the previous value did not run past the blob end. The final

attribute has no successor, so its decoded value length is never checked

against the blob bounds. A malicious or compromised metadata server can

set the last attribute's value length larger than the bytes actually

present in the blob.

Why It Matters

CVE-2026-89649 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.1/10

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-89649.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-89649 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/01e3f19c301d492e12f16b3b463ac14d7cf3ebe7
  • https://git.kernel.org/stable/c/1dd356310b1660215f9a3626580bf8b363ef981e
  • https://git.kernel.org/stable/c/38be2f3c41ecaba58bb92dc16603e09ba9fd64f1
  • https://git.kernel.org/stable/c/61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce
  • https://git.kernel.org/stable/c/68d541754d6cd3bb98d1fd8314f57e5eb533557d
  • https://git.kernel.org/stable/c/848b80ca6b410f350d08b8ac19a00ef88223f2ea
  • https://git.kernel.org/stable/c/b12b3320c81fd72ab36388fb2445fec9c3038f10
  • https://git.kernel.org/stable/c/cb0cd79ae80476d1bc06bd9678484b6736f19588

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for SBOM-based CVE matching and Vulnios CVE feed continuous monitoring against your asset inventory. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2026-89649?

    CVE-2026-89649 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    ceph: bound xattr value length in __build_xattrs()

    __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a

    time. F

    Am I affected?

    Affected technology is listed in the Affected Products section above. If your asset inventory contains any of them, assume in-scope until you can prove otherwise.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2026-89649. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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