GHSA-27JV-R6JG-F5FR
Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-04-02 15:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-23393"
],
"database_specific": {
"cwe_ids": [
"CWE-362"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-25T11:16:40Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: cfm: Fix race condition in peer_mep deletion\n\nWhen a peer MEP is being deleted, cancel_delayed_work_sync() is called\non ccm_rx_dwork before freeing. However, br_cfm_frame_rx() runs in\nsoftirq context under rcu_read_lock (without RTNL) and can re-schedule\nccm_rx_dwork via ccm_rx_timer_start() between cancel_delayed_work_sync()\nreturning and kfree_rcu() being called.\n\nThe following is a simple race scenario:\n\n cpu0 cpu1\n\nmep_delete_implementation()\n cancel_delayed_work_sync(ccm_rx_dwork);\n br_cfm_frame_rx()\n // peer_mep still in hlist\n if (peer_mep-\u003eccm_defect)\n ccm_rx_timer_start()\n queue_delayed_work(ccm_rx_dwork)\n hlist_del_rcu(\u0026peer_mep-\u003ehead);\n kfree_rcu(peer_mep, rcu);\n ccm_rx_work_expired()\n // on freed peer_mep\n\nTo prevent this, cancel_delayed_work_sync() is replaced with\ndisable_delayed_work_sync() in both peer MEP deletion paths, so\nthat subsequent queue_delayed_work() calls from br_cfm_frame_rx()\nare silently rejected.\n\nThe cc_peer_disable() helper retains cancel_delayed_work_sync()\nbecause it is also used for the CC enable/disable toggle path where\nthe work must remain re-schedulable.",
"id": "GHSA-27jv-r6jg-f5fr",
"modified": "2026-04-02T15:31:36Z",
"published": "2026-03-25T12:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23393"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1fd81151f65927fd9edb8ecd12ad45527dbbe5ab"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3715a00855316066cdda69d43648336367422127"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d8f35767bacb3c7769d470a41cf161e3f3c07e70"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e89dbd2736a45f0507949af4748cbbf3ff793146"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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