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CVE-2026-90151

Critical Vulnerability: CVE-2026-90151

In the Linux kernel, the following vulnerability has been resolved: NFSv4: remove callback IDR entry on client allocation failure nfs4_alloc_client() allocates an NFSv4.0 callback identifier before it finishes setting up the client. If any later initialization step fails, the error path frees the nfs_client directly with nfs_free_client(). That bypasses nfs_put_client(), which is where the callback IDR entry is removed during normal teardown. A failed allocation can therefore leave cb_ident_i

Friday, September 18, 2026Vulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2026-90151 is rated CRITICAL โ€” 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:

NFSv4: remove callback IDR entry on client allocation failure

nfs4_alloc_client() allocates an NFSv4.0 callback identifier before it

finishes setting up the client. If any later initialization step fails,

the error path frees the nfs_client directly with nfs_free_client(). That

bypasses nfs_put_client(), which is where the callback IDR entry is

removed during normal teardown.

A failed allocation can therefore leave cb_ident_idr pointing at a freed

nfs_client. A later NFSv4.0 callback lookup by cb_ident would find the

stale pointer and take a reference to it.

Make the callback IDR removal helper callable by the allocation failure

path, and remove the callback identifier before freeing the client.

This was found by a local static-analysis checker for publish-before-free

lifetime bugs and confirmed by manual inspection.

Why It Matters

CVE-2026-90151 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.8/10

๐Ÿ›ก๏ธWhat Defenders Should Check

  • Check if you are affected โ€” Review your asset inventory for products listed in CVE-2026-90151.
  • Apply available patches โ€” Visit vendor advisories for the latest security updates.
  • Monitor for exploitation โ€” Check your SIEM/IDS logs for related indicators.
  • Use Vulnios to continuously monitor your exposure to CVE-2026-90151 and similar vulnerabilities.

    References & Sources

    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-2026-90151?

    CVE-2026-90151 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    NFSv4: remove callback IDR entry on client allocation failure

    nfs4_alloc_client() allocates an NFSv4.0 callback identifier before

    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-2026-90151. 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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