Bug 2401423 (CVE-2025-39931)

Summary: CVE-2025-39931 kernel: crypto: af_alg - Set merge to zero early in af_alg_sendmsg
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-10-04 08:02:25 UTC 
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.
Comment 1 Jon Moroney 2025-10-06 15:52:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025100416-CVE-2025-39931-8ff7@gregkh/T