CVE-2025-68775

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

net/handshake: duplicate handshake cancellations leak socket

When a handshake request is cancelled it is removed from the

handshake_net->hn_requests list, but it is still present in the

handshake_rhashtbl until it is destroyed.

If a second cancellation request arrives for the same handshake request,

then remove_pending() will return false... and assuming

HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue

processing through the out_true label, where we put another reference on

the sock and a refcount underflow occurs.

This can happen for example if a handshake times out - particularly if

the SUNRPC client sends the AUTH_TLS probe to the server but doesn't

follow it up with the ClientHello due to a problem with tlshd. When the

timeout is hit on the server, the server will send a FIN, which triggers

a cancellation request via xs_reset_transport(). When the timeout is

hit on the client, another canc

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References