CVE-2025-39964: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-39964 affects the Linux kernel's crypto subsystem, specifically the afalg socket implementation. The vulnerability was discovered and disclosed on October 13, 2025. The issue involves concurrent writes to the same afalg socket, which can lead to data interleaving and inconsistencies in the internal socket state (NVD).

The vulnerability exists in the afalgsendmsg functionality where concurrent writes to the same af_alg socket can cause data to be interleaved unpredictably. This creates inconsistencies in the internal socket state. The fix involves adding a new ctx->write field that indicates exclusive ownership for writing operations (NVD).

When exploited, this vulnerability can lead to unpredictable data interleaving in the af_alg socket and create inconsistencies in the internal socket state, potentially affecting the integrity of cryptographic operations (NVD).

The vulnerability has been resolved in the Linux kernel by implementing a fix that disallows concurrent writes in afalgsendmsg. This is achieved through the addition of a new ctx->write field that establishes exclusive ownership for writing operations (NVD).