CVE-2026-72389

Technical Description

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

bridge: stp: Fix a potential use-after-free when deleting a bridge

The three STP timers are not supposed to be armed while the bridge is

administratively down. They are synchronously deactivated when the

bridge is put administratively down and the various call sites check for

'IFF_UP' before arming them.

This check is missing from br_topology_change_detection() and it is

possible to engineer a situation in which the topology change timer is

armed while the bridge is administratively down, resulting in a

use-after-free [1] when the bridge is deleted.

Fix by adding the missing check and for good measures synchronously

shutdown the three timers when the bridge is deleted.

[1]

ODEBUG: free active (active state 0) object: ffff88811662b9b0 object type: timer_list hint: br_topology_change_timer_expired (net/bridge/br_stp_timer.c:120)

WARNING: lib/debugobjects.c:629 at debug_print_object+0x1bc/0x450, CPU#9: ip/359

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