CVE-2025-39931
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-04

Last updated on: 2026-03-25

Assigner: kernel.org

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.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2025-10-04
Last Modified
2026-03-25
Generated
2026-06-16
AI Q&A
2025-10-04
EPSS Evaluated
2026-06-15
NVD
CVE-2025-39931
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Quick Actions
Instant insights powered by AI
Executive Summary

This vulnerability is in the Linux kernel's crypto subsystem, specifically in the af_alg module. If an error causes the function af_alg_sendmsg to abort, a variable named ctx->merge may retain an invalid (garbage) value from a previous operation. When af_alg_sendmsg is called again, this invalid value can cause the system to crash because it attempts to perform an invalid merge operation. The fix involves resetting ctx->merge to zero early in the processing loop to prevent this issue.

Impact Analysis

This vulnerability can cause the Linux kernel to crash when the af_alg_sendmsg function encounters an error and then is called again. Such crashes can lead to system instability or denial of service, potentially disrupting services or applications relying on the affected kernel's cryptographic functions.

Chat Assistant
Ask questions about this CVE
Hi! I’m here to help you understand CVE-2025-39931. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70
EPSS Chart