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GHSA-27JV-R6JG-F5FR

Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-03-25 12:30

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-23393"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-25T11:16:40Z",
    "severity": null
  },
  "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": "2026-03-25T12:30:24Z",
  "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": []
}

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

Vulnerability from cvelistv5 – Published: 2026-03-25 10:33 – Updated: 2026-03-25 10:33

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

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/e89dbd2736a45f050…
	https://git.kernel.org/stable/c/d8f35767bacb3c776…
	https://git.kernel.org/stable/c/1fd81151f65927fd9…
	https://git.kernel.org/stable/c/3715a00855316066c…

Impacted products

Vendor

Product

Version

Linux

Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < e89dbd2736a45f0507949af4748cbbf3ff793146 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < d8f35767bacb3c7769d470a41cf161e3f3c07e70 (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 1fd81151f65927fd9edb8ecd12ad45527dbbe5ab (git)
Affected: dc32cbb3dbd7da38c700d6e0fc6354df24920525 , < 3715a00855316066cdda69d43648336367422127 (git)

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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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_cfm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e89dbd2736a45f0507949af4748cbbf3ff793146",
              "status": "affected",
              "version": "dc32cbb3dbd7da38c700d6e0fc6354df24920525",
              "versionType": "git"
            },
            {
              "lessThan": "d8f35767bacb3c7769d470a41cf161e3f3c07e70",
              "status": "affected",
              "version": "dc32cbb3dbd7da38c700d6e0fc6354df24920525",
              "versionType": "git"
            },
            {
              "lessThan": "1fd81151f65927fd9edb8ecd12ad45527dbbe5ab",
              "status": "affected",
              "version": "dc32cbb3dbd7da38c700d6e0fc6354df24920525",
              "versionType": "git"
            },
            {
              "lessThan": "3715a00855316066cdda69d43648336367422127",
              "status": "affected",
              "version": "dc32cbb3dbd7da38c700d6e0fc6354df24920525",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_cfm.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.11"
            },
            {
              "lessThan": "5.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "5.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "5.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.10",
                  "versionStartIncluding": "5.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0-rc5",
                  "versionStartIncluding": "5.11",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-27JV-R6JG-F5FR

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

Tags

Sightings

Nomenclature