BaseFortify

Publication date: 2025-10-04

Last updated on: 2026-07-04

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.

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Meta Information

Published

2025-10-04

Last Modified

2026-07-04

Generated

2026-07-06

AI Q&A

2025-10-04

EPSS Evaluated

2026-07-05

NVD

CVE-2025-39931

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	From 5.15.160 (inc) to 5.16 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

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.

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