CVE-2025-21756

Summary

CVE-2025-21756 is a Linux kernel vulnerability affecting the vsock subsystem. It allows for use-after-free conditions due to a failure to properly manage socket bindings during transport reassignment. Specifically, during vsock_bind(), the kernel assumes the socket is in the unbound list but may have already been moved to the bound list, resulting in a refcount underflow and use-after-free when vsock_remove_bound() is called. This issue was identified by KASAN and led to a kernel panic. By preserving sockets bindings, the vulnerability has been resolved.

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