Time-of-check Time-of-use (TOCTOU) Affecting kernel-rt-64k package, versions *


Severity

Recommended
medium

Based on CentOS security rating.

Threat Intelligence

EPSS
0.12% (3rd percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-CENTOS10-KERNELRT64K-19392183
  • published28 Aug 2026
  • disclosed26 Aug 2026

Introduced: 26 Aug 2026

NewCVE-2026-80521  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 kernel-rt-64k.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k package and not the kernel-rt-64k package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

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

af_unix: Unlink scc_entry in unix_del_edge().

Kyle Zeng reported that GC could free a dead SCC partially.

The scenario is as follows:

  1. Create two SCCs:

    X -. A <-> B ^--'

  2. Run the following concurrently:

    2-1) send() sk-B to sk-B from sk-X 2-2) close() both A and B

At 2-1), there is a small window where unix_add_edges() publishes a new edge (B <-> B) to GC but its skb is not queued by skb_queue_tail().

If 2-2) completes before skb_queue_tail() and GC is triggered, it judges A <-> B as dead, but B is not freed because GC cannot collect the not-yet-queued skb holding the B <-> B edge.

   X -.   A &lt;-&gt; B -. This edge is visible
   ^--&#39;         ^..&#39;  but skb is not

This itself is not a problem since the next GC run will judge B as dead as well and free it finally.

   X -.   A &lt;.&gt; B -.
   ^--&#39;         ^--&#39;

However, X's SCC forces the next GC to call unix_walk_scc_fast(), and it iterates over A through B's scc_entry.

Let's unlink scc_entry before freeing the vertex in unix_del_edge().

CVSS Base Scores

version 3.1