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CVE-2026-64537

Status: ReceivedUnscored—

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

bridge: cfm: reject invalid CCM interval at configuration time

ccm_tx_work_expired() re-arms itself via queue_delayed_work() using the configured exp_interval converted by interval_to_us(). When exp_interval is BR_CFM_CCM_INTERVAL_NONE or out of range, interval_to_us() returns 0, causing the worker to fire immediately in a tight loop that allocates skbs until OOM.

Fix this by validating exp_interval at configuration time:

Technical details traces, logs and code from the original report
 - Constrain IFLA_BRIDGE_CFM_CC_CONFIG_EXP_INTERVAL to the valid range
   [BR_CFM_CCM_INTERVAL_3_3_MS, BR_CFM_CCM_INTERVAL_10_MIN] in the
   netlink policy so userspace cannot set an invalid value.

 - Reject starting CCM TX in br_cfm_cc_ccm_tx() when exp_interval has
   not yet been configured (defaults to 0 from kzalloc).

CVSS

NVD hasn't assigned a CVSS score to this CVE (common since the April 2026 policy change).

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Linux — Linux KernelAI

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-64537",
  "cveTags": [],
  "metrics": {},
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "2870056a78961e0fecd652362ee9d3fcfd24a8a6",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "f0f5eb59a97ece0d85de8cfa95dc18c609302a8b",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "53788b134519e995699ea3721969c96a08d64575",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "b42aeb58317f12024734759ff745856b53948873",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "a090880c1f544589427e5b7050c40fb211ccecb4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "865643640b5b5c4579b32d7a55ac9ad648362eaa",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2be665c3940d367e0a2a8128eb4985ce323f99a3",
              "lessThan": "f3e02edd8322b31b8e6517faa6ba053bf29d1e26",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/bridge/br_cfm.c",
            "net/bridge/br_cfm_netlink.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.11"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.11",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/bridge/br_cfm.c",
            "net/bridge/br_cfm_netlink.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-07-27T21:17:05.987",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2870056a78961e0fecd652362ee9d3fcfd24a8a6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/53788b134519e995699ea3721969c96a08d64575",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/865643640b5b5c4579b32d7a55ac9ad648362eaa",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a090880c1f544589427e5b7050c40fb211ccecb4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b42aeb58317f12024734759ff745856b53948873",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f0f5eb59a97ece0d85de8cfa95dc18c609302a8b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f3e02edd8322b31b8e6517faa6ba053bf29d1e26",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbridge: cfm: reject invalid CCM interval at configuration time\n\nccm_tx_work_expired() re-arms itself via queue_delayed_work() using\nthe configured exp_interval converted by interval_to_us(). When\nexp_interval is BR_CFM_CCM_INTERVAL_NONE or out of range,\ninterval_to_us() returns 0, causing the worker to fire immediately in\na tight loop that allocates skbs until OOM.\n\nFix this by validating exp_interval at configuration time:\n\n - Constrain IFLA_BRIDGE_CFM_CC_CONFIG_EXP_INTERVAL to the valid range\n   [BR_CFM_CCM_INTERVAL_3_3_MS, BR_CFM_CCM_INTERVAL_10_MIN] in the\n   netlink policy so userspace cannot set an invalid value.\n\n - Reject starting CCM TX in br_cfm_cc_ccm_tx() when exp_interval has\n   not yet been configured (defaults to 0 from kzalloc)."
    }
  ],
  "lastModified": "2026-08-17T05:17:58.630",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}