CVE-2026-63979

A flaw was found in the Linux kernel's net/handshake component. A race condition exists where a network handshake request can be removed and its associated file reference released concurrently while the accept-side code attempts to access it. This can lead to the system attempting to read from freed memory or a null pointer, potentially causing system instability or a denial of service.

This vulnerability is evaluated as a Moderate impact because successfully triggering the underlying race condition requires precise race timing during handshake cancellations, limiting exposure primarily to a local denial of service. The affected kernel handshake subsystem is engaged when kernel-layer TLS facilities (such as RPC-with-TLS) handle connection negotiation with user-space daemons. Standard enterprise deployments that do not actively utilize in-kernel transport encryption handshakes will not invoke the affected code paths.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.