CVE-2026-23393 (GCVE-0-2026-23393)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:33 – Updated: 2026-03-25 10:33
VLAI?
Title
bridge: cfm: Fix race condition in peer_mep deletion
Summary
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < e89dbd2736a45f0507949af4748cbbf3ff793146 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < d8f35767bacb3c7769d470a41cf161e3f3c07e70 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 1fd81151f65927fd9edb8ecd12ad45527dbbe5ab (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 3715a00855316066cdda69d43648336367422127 (git)
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    Linux Linux Affected: 5.11
Unaffected: 0 , < 5.11 (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.20 , ≤ 6.18.* (semver)
Unaffected: 6.19.10 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc5 , ≤ * (original_commit_for_fix)
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{
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_cfm.c"
          ],
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          "vendor": "Linux",
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          "vendor": "Linux",
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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              "versionType": "semver"
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              "versionType": "semver"
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              "version": "7.0-rc5",
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      "cpeApplicability": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "5.11",
                  "vulnerable": true
                },
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-25T10:33:17.407Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e89dbd2736a45f0507949af4748cbbf3ff793146"
        },
        {
          "url": "https://git.kernel.org/stable/c/d8f35767bacb3c7769d470a41cf161e3f3c07e70"
        },
        {
          "url": "https://git.kernel.org/stable/c/1fd81151f65927fd9edb8ecd12ad45527dbbe5ab"
        },
        {
          "url": "https://git.kernel.org/stable/c/3715a00855316066cdda69d43648336367422127"
        }
      ],
      "title": "bridge: cfm: Fix race condition in peer_mep deletion",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23393",
    "datePublished": "2026-03-25T10:33:17.407Z",
    "dateReserved": "2026-01-13T15:37:46.011Z",
    "dateUpdated": "2026-03-25T10:33:17.407Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23393\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-25T11:16:40.040\",\"lastModified\":\"2026-03-25T15:41:33.977\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1fd81151f65927fd9edb8ecd12ad45527dbbe5ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3715a00855316066cdda69d43648336367422127\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d8f35767bacb3c7769d470a41cf161e3f3c07e70\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e89dbd2736a45f0507949af4748cbbf3ff793146\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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