VulnerabilityPublished 4 Sep 2025Updated 5 Nov 2026

CVE-2025-38691: Linux kernel · pNFS: Fix uninited ptr deref in block/scsi layout

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f0b2eee3fbba9b7e3746ef698424ef5e4a197776 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:34 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in f0b2eee3fbba9b7e3746ef698424ef5e4a197776, 9768797c219326699778fba9cd3b607b2f1e7950, 24334f3cf8a294f253071b5bf22d754dbb6d0f2d +6

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < f0b2eee3fbba9b7e3746ef698424ef5e4a197776	Fixed in f0b2eee3fbba9b7e3746ef698424ef5e4a197776
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < 9768797c219326699778fba9cd3b607b2f1e7950	Fixed in 9768797c219326699778fba9cd3b607b2f1e7950
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < 24334f3cf8a294f253071b5bf22d754dbb6d0f2d	Fixed in 24334f3cf8a294f253071b5bf22d754dbb6d0f2d
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < 2896f101110076ac6bf99d7aaf463d61e26f89dd	Fixed in 2896f101110076ac6bf99d7aaf463d61e26f89dd
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < 579b85f893d9885162e1cabf99a4a088916e143e	Fixed in 579b85f893d9885162e1cabf99a4a088916e143e
LinuxLinux	Affected ≥ 34dc93c2fc04da0d01acf8a1660b4ab276208af7, < 94ec6d939031a616474376dadbf4a8d0ef8b0bcc	Fixed in 94ec6d939031a616474376dadbf4a8d0ef8b0bcc

Description

In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix uninited ptr deref in block/scsi layout The error occurs on the third attempt to encode extents. When function ext_tree_prepare_commit() reallocates a larger buffer to retry encoding extents, the "layoutupdate_pages" page array is initialized only after the retry loop. But ext_tree_free_commitdata() is called on every iteration and tries to put pages in the array, thus dereferencing uninitialized pointers. An additional problem is that there is no limit on the maximum possible buffer_size. When there are too many extents, the client may create a layoutcommit that is larger than the maximum possible RPC size accepted by the server. During testing, we observed two typical scenarios. First, one memory page for extents is enough when we work with small files, append data to the end of the file, or preallocate extents before writing. But when we fill a new large file without preallocating, the number of extents can be huge, and counting the number of written extents in ext_tree_encode_commit() does not help much. Since this number increases even more between unlocking and locking of ext_tree, the reallocated buffer may not be large enough again and again.

References

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