CVE-2025-39838

cifs: prevent NULL pointer dereference in UTF16 conversion

MEDIUM
5.5
CVSS Score
Published: September 19, 2025 at 03:26 PM UTC
Updated: October 19, 2026 at 09:10 PM UTC
3 products affected across 3 vendorsLinux KernelDebian LinuxSIMATIC CN 4100

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%

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

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

6.12 ≤ v < 6.12.466.13 ≤ v < 6.16.641d3f256c6a5e41eb32b87168399c0facd512dc06.126.176.17 rc16.17 rc26.17 rc36.17 rc4
Vendor states this is fixed in 1f797f062b5cf13a1c2bcc23285361baaa7c9260 (fixed)
Vendor states this is fixed in 3c26a8d30ed6b53a52a023ec537dc50a6d34a67a (fixed)
Vendor states this is fixed in 70bccd9855dae56942f2b18a08ba137bb54093a0 (fixed)
Vendor states this is fixed in 6.12 (unaffected)
Vendor states this is fixed in 6.12.46 (unaffected)
Vendor states this is fixed in 6.16.6 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)
v < V5.0
Affected range stops below V5.0, so it looks safe — our inference, not a vendor statement

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

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