CVE-2026-23393

Description

In the Linux kernel, the following vulnerability has been resolved: bridge: cfm: Fix race condition in peer_mep deletion When a peer MEP is being deleted, cancel_delayed_work_sync() is called on ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in softirq context under rcu_read_lock (without RTNL) and can re-schedule ccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync() returning and kfree_rcu() being called. The following is a simple race scenario: cpu0 cpu1 mep_delete_implementation() cancel_delayed_work_sync(ccm_rx_dwork); br_cfm_frame_rx() // peer_mep still in hlist if (peer_mep->ccm_defect) ccm_rx_timer_start() queue_delayed_work(ccm_rx_dwork) hlist_del_rcu(&peer_mep->head); kfree_rcu(peer_mep, rcu); ccm_rx_work_expired() // on freed peer_mep To prevent this, cancel_delayed_work_sync() is replaced with disable_delayed_work_sync() in both peer MEP deletion paths, so that subsequent queue_delayed_work() calls from br_cfm_frame_rx() are silently rejected. The cc_peer_disable() helper retains cancel_delayed_work_sync() because it is also used for the CC enable/disable toggle path where the work must remain re-schedulable.

CVSS Metrics

• v3.1•HIGH•Score: 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.10%• Percentile: 1%

Techniques & Countermeasures

• CWE-362•Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

  The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Affected Systems

• linux•linux

  ≥ dc32cbb3dbd7da38c700d6e0fc6354df24920525, < e89dbd2736a45f0507949af4748cbbf3ff793146 | ≥ dc32cbb3dbd7da38c700d6e0fc6354df24920525, < d8f35767bacb3c7769d470a41cf161e3f3c07e70 | ≥ dc32cbb3dbd7da38c700d6e0fc6354df24920525, < 1fd81151f65927fd9edb8ecd12ad45527dbbe5ab | ≥ dc32cbb3dbd7da38c700d6e0fc6354df24920525, < 3715a00855316066cdda69d43648336367422127 | 5.11

• linux•linux kernel

  ≥ 5.11.1, < 6.12.78 | ≥ 6.13, < 6.18.20 | ≥ 6.19, < 6.19.10 | 5.11 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6 | 7.0:rc7

References (4)

• https://git.kernel.org/stable/c/e89dbd2736a45f0507949af4748cbbf3ff793146
• https://git.kernel.org/stable/c/d8f35767bacb3c7769d470a41cf161e3f3c07e70
• https://git.kernel.org/stable/c/1fd81151f65927fd9edb8ecd12ad45527dbbe5ab
• https://git.kernel.org/stable/c/3715a00855316066cdda69d43648336367422127