Medium severity · published Sep 19, 2025
CVE-2025-39838
cifs: prevent NULL pointer dereference in UTF16 conversion
5.5
CVSS
0.2%
EPSS
No
On KEV
Description
In the Linux kernel, the following vulnerability has been resolved:
cifs: prevent NULL pointer dereference in UTF16 conversion
There can be a NULL pointer dereference bug here. NULL is passed to
__cifs_sfu_make_node without checks, which passes it unchecked to
cifs_strndup_to_utf16, which in turn passes it to
cifs_local_to_utf16_bytes where '*from' is dereferenced, causing a crash.
This patch adds a check for NULL 'src' in cifs_strndup_to_utf16 and
returns NULL early to prevent dereferencing NULL pointer.
Found by Linux Verification Center (linuxtesting.org) with SVACE
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 5% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
6.12 before 6.12.46; 6.13 before 6.16.6; 6.17; 6.17; 6.17; 6.17 · source: NVD
LI
Linux · Linux
41d3f256c6a5e41eb32b87168399c0facd512dc0 before 1f797f062b5cf13a1c2bcc23285361baaa7c9260; 41d3f256c6a5e41eb32b87168399c0facd512dc0 before 3c26a8d30ed6b53a52a023ec537dc50a6d34a67a; 41d3f256c6a5e41eb32b87168399c0facd512dc0 before 70bccd9855dae56942f2b18a08ba137bb54093a0; 6.12 · source: vendor
DL
Debian Linux · Debian
11.0 · source: NVD
SC
SIMATIC CN 4100 · Siemens
before V5.0 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-39838
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-39838
Patch
https://git.kernel.org/stable/c/1f797f062b5cf13a1c2bcc23285361baaa7c9260
Patch
https://git.kernel.org/stable/c/3c26a8d30ed6b53a52a023ec537dc50a6d34a67a
Patch
https://git.kernel.org/stable/c/70bccd9855dae56942f2b18a08ba137bb54093a0
Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
cert-portal.siemens.com
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
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