CVE-2025-38236

Technical Description

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

af_unix: Don't leave consecutive consumed OOB skbs.

Jann Horn reported a use-after-free in unix_stream_read_generic().

The following sequences reproduce the issue:

$ python3

from socket import *

s1, s2 = socketpair(AF_UNIX, SOCK_STREAM)

s1.send(b'x', MSG_OOB)

s2.recv(1, MSG_OOB) # leave a consumed OOB skb

s1.send(b'y', MSG_OOB)

s2.recv(1, MSG_OOB) # leave a consumed OOB skb

s1.send(b'z', MSG_OOB)

s2.recv(1) # recv 'z' illegally

s2.recv(1, MSG_OOB) # access 'z' skb (use-after-free)

Even though a user reads OOB data, the skb holding the data stays on

the recv queue to mark the OOB boundary and break the next recv().

After the last send() in the scenario above, the sk2's recv queue has

2 leading consumed OOB skbs and 1 real OOB skb.

Then, the following happens during the next recv() without MSG_OOB

1. unix_stream_read_generic() peeks the first consumed OOB skb

2. ma

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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.

Affected Products

References