CVE-2025-39838: Linux kernel · cifs: prevent NULL pointer dereference in UTF16 conversion
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in 70bccd9855dae56942f2b18a08ba137bb54093a0 : update Linux kernel when convenient.
Data as of 5 Nov 2026, 21:35 UTC
Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- 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 70bccd9855dae56942f2b18a08ba137bb54093a0, 3c26a8d30ed6b53a52a023ec537dc50a6d34a67a, 1f797f062b5cf13a1c2bcc23285361baaa7c9260
Exploitation evidence
Disclosed: evidence found.
CVE published 19 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.
What to do
Upgrade Linux kernel to 70bccd9855dae56942f2b18a08ba137bb54093a0, 3c26a8d30ed6b53a52a023ec537dc50a6d34a67a or 1f797f062b5cf13a1c2bcc23285361baaa7c9260.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
A fix is available and has been applied in the Linux kernel. Users should update to the patched kernel version that includes the fix identified by the commits 70bccd9855dae56942f2b18a08ba137bb54093a0, 3c26a8d30ed6b53a52a023ec537dc50a6d34a67a, and 1f797f062b5cf13a1c2bcc23285361baaa7c9260. No additional mitigation steps are required beyond applying the official patch.
Description
A NULL pointer dereference vulnerability was identified and fixed in the Linux kernel's CIFS module affecting version 6.12. The flaw occurs during UTF16 conversion when a NULL pointer is passed unchecked, leading to a kernel crash. The issue was resolved by adding a NULL check to prevent dereferencing a NULL pointer.
References
- git.kernel.org/stable/c/1f797f062b5cf13a1c2bcc23285361baaa7c9260 (opens in a new tab)
- git.kernel.org/stable/c/3c26a8d30ed6b53a52a023ec537dc50a6d34a67a (opens in a new tab)
- git.kernel.org/stable/c/70bccd9855dae56942f2b18a08ba137bb54093a0 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-032379.html (opens in a new tab)