CVE-2025-39931

crypto: af_alg - Set merge to zero early in af_alg_sendmsg

MEDIUM
5.5
CVSS Score
Published: October 4, 2025 at 07:30 AM UTC
Updated: October 19, 2026 at 09:10 PM UTC
4 products affected across 2 vendorsLinux KernelSIMATIC S7-1500 CPU 1518-4 Pn /dp MFP FirmwareSiplus S7-1500 CPU 1518-4 Pn /dp MFP Firmware

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.

Affected

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

2.6.38 ≤ v < 6.1.1546.13 ≤ v < 6.16.96.2 ≤ v < 6.6.1086.7 ≤ v < 6.12.496.176.17 rc16.17 rc26.17 rc36.17 rc46.17 rc56.17 rc68ff590903d5fc7f5a0a988c38267a3d08e6393a2
Vendor states this is fixed in 045ee26aa3920a47ec46d7fcb302420bf01fd753 (fixed)
Vendor states this is fixed in 2374c11189ef704a3e4863646369f1b8e6a27d71 (fixed)
Vendor states this is fixed in 24c1106504c625fabd3b7229611af617b4c27ac7 (fixed)
Vendor states this is fixed in 28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf (fixed)
Vendor states this is fixed in 6241b9e2809b12da9130894cf5beddf088dc1b8a (fixed)
Vendor states this is fixed in 9574b2330dbd2b5459b74d3b5e9619d39299fc6f (fixed)
Vendor states this is fixed in db2b42425dfbde4983b0c20fb7cfa05f70e6a745 (fixed)
Vendor states this is fixed in 2.6.38 (unaffected)
Vendor states this is fixed in 5.10.260 (unaffected)
Vendor states this is fixed in 5.15.211 (unaffected)
Vendor states this is fixed in 6.1.154 (unaffected)
Vendor states this is fixed in 6.12.49 (unaffected)
Vendor states this is fixed in 6.16.9 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)
Vendor states this is fixed in 6.6.108 (unaffected)

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

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-908

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