🛡️ CVE-2025-68775 — kernel

🔴 CVSS 9.8 — Critical ✅ No Known Exploit NVD
9.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

net/handshake: duplicate handshake cancellations leak socket

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 cancellation request happens via

xs_tls_handshake_sync().

Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel

path so duplicate cancels can be detected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2025-68775 is recorded against 2 packages.

  • kernel (from 6.13.0 up to 6.18.3)
  • unknown

Timeline and source

Published on 13 January 2026 and last revised on 6 August 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2025-68775 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Critical
CVSS Score 9.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-01-13
Updated 2026-08-12
Modified 2026-08-06
Fix URL N/A

Affected Packages

Software From version Fixed in
kernel 6.13.0 6.18.3
unknown — —

Similar Threats

Exploit Protection

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