CVE-2026-63800 (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix use-after-free in pnfs_update_layout() When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(), the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds, pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(), which still references 'lo'. This results in a use-after-free when the tracepoint accesses lo's fields. Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0050

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/13e198a90ca4050f4bee8a3f23680389a6563ccc https://git.kernel.org/stable/c/1f24b8302c77dcaf79c64c073877a3b9f4dd25d2 https://git.kernel.org/stable/c/200e7637f4d6a1342987045eea72641524f909dc https://git.kernel.org/stable/c/2883ddd7542b4437a2ab4908fe2773f690e20889 https://git.kernel.org/stable/c/4ad8b9a85dbf57ca532ee9e65ad7e6498bfbbf98 https://git.kernel.org/stable/c/7e37e9b3e82ade881e1798e2f4fcc54aff7793c1 https://git.kernel.org/stable/c/9645aaf689aff57427ece3b9fa47d5b5399417f4 https://git.kernel.org/stable/c/9c0fb5c09ae5bd68dc0038692af8127029cb0385

Frequently Asked Questions

What is CVE-2026-63800? +

In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix use-after-free in pnfs_update_layout() When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(), the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds, pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(), which still references 'lo'. This results in a use-after-free when the tracepoint accesses lo's fields. Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo). It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-63800? +

CVE-2026-63800 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0050, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-63800? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-63800