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


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.02% (6th percentile)

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  • Snyk IDSNYK-CENTOS9-KERNELRT64KDEVELMATCHED-16990868
  • published28 May 2026
  • disclosed27 May 2026

Introduced: 27 May 2026

NewCVE-2026-46086  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

There is no fixed version for Centos:9 kernel-rt-64k-devel-matched.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-devel-matched package and not the kernel-rt-64k-devel-matched package as distributed by Centos. See How to fix? for Centos:9 relevant fixed versions and status.

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

net: bridge: use a stable FDB dst snapshot in RCU readers

Local FDB entries can be rewritten in place by fdb_delete_local(), which updates f->dst to another port or to NULL while keeping the entry alive. Several bridge RCU readers inspect f->dst, including br_fdb_fillbuf() through the brforward_read() sysfs path.

These readers currently load f->dst multiple times and can therefore observe inconsistent values across the check and later dereference. In br_fdb_fillbuf(), this means a concurrent local-FDB update can change f->dst after the NULL check and before the port_no dereference, leading to a NULL-ptr-deref.

Fix this by taking a single READ_ONCE() snapshot of f->dst in each affected RCU reader and using that snapshot for the rest of the access sequence. Also publish the in-place f->dst updates in fdb_delete_local() with WRITE_ONCE() so the readers and writer use matching access patterns.

CVSS Base Scores

version 3.1