Vulnerability-Lookup

FKIE_CVE-2026-74480

Vulnerability from fkie_nvd - Published: 2026-08-15 13:17 - Updated: 2026-08-17 06:19

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: net: bridge: stop fast-leave after deleting a port group br_multicast_leave_group() iterates mp->ports with pp = &p->next in its fast-leave path. After br_multicast_del_pg() removes p, continuing the loop advances pp through the deleted entry. If multicast-to-unicast was enabled, the bridge can hold multiple port groups for the same port and group with different source MAC addresses. Once multicast-to-unicast is disabled, br_port_group_equal() matches those entries by port only. A fast leave can then delete one entry and continue from its stale next pointer, leaving mp->ports pointing at a deleted port group. Fast leave only needs to remove one matching port group. Break after br_multicast_del_pg() so the loop stops before dereferencing the removed entry.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "159ad90cb929c033308bb39a2c5f8fbf393b77aa",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "4695430e8132420bf8de94da3eb36a6cf35fde6b",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "0309ebbc570000ea0df11c06b69798e5860c5f6f",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "a39789f211b8a4125f0c70e05b30cf715f4f187d",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.11"
            },
            {
              "lessThan": "4.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: stop fast-leave after deleting a port group\n\nbr_multicast_leave_group() iterates mp-\u003eports with pp = \u0026p-\u003enext in\nits fast-leave path. After br_multicast_del_pg() removes p,\ncontinuing the loop advances pp through the deleted entry.\n\nIf multicast-to-unicast was enabled, the bridge can hold multiple port\ngroups for the same port and group with different source MAC\naddresses. Once multicast-to-unicast is disabled,\nbr_port_group_equal() matches those entries by port only. A fast leave\ncan then delete one entry and continue from its stale next pointer,\nleaving mp-\u003eports pointing at a deleted port group.\n\nFast leave only needs to remove one matching port group. Break after\nbr_multicast_del_pg() so the loop stops before dereferencing the\nremoved entry."
    }
  ],
  "id": "CVE-2026-74480",
  "lastModified": "2026-08-17T06:19:44.103",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T13:17:52.820",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-74480 (GCVE-0-2026-74480)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-08-17 05:47

Title

net: bridge: stop fast-leave after deleting a port group

Summary

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

5 references

URL	Tags
https://git.kernel.org/stable/c/159ad90cb929c0333…
https://git.kernel.org/stable/c/4695430e8132420bf…
https://git.kernel.org/stable/c/0309ebbc570000ea0…
https://git.kernel.org/stable/c/4c57056ca6aace2e9…
https://git.kernel.org/stable/c/a39789f211b8a4125…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 6db6f0eae6052b70885562e1733896647ec1d807 , < 159ad90cb929c033308bb39a2c5f8fbf393b77aa (git) Affected: 6db6f0eae6052b70885562e1733896647ec1d807 , < 4695430e8132420bf8de94da3eb36a6cf35fde6b (git) Affected: 6db6f0eae6052b70885562e1733896647ec1d807 , < 0309ebbc570000ea0df11c06b69798e5860c5f6f (git) Affected: 6db6f0eae6052b70885562e1733896647ec1d807 , < 4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4 (git) Affected: 6db6f0eae6052b70885562e1733896647ec1d807 , < a39789f211b8a4125f0c70e05b30cf715f4f187d (git)
Linux	Linux	Affected: 4.11 Unaffected: 0 , < 4.11 (semver) Unaffected: 6.6.151 , ≤ 6.6.* (semver) Unaffected: 6.12.103 , ≤ 6.12.* (semver) Unaffected: 6.18.44 , ≤ 6.18.* (semver) Unaffected: 7.1.8 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "159ad90cb929c033308bb39a2c5f8fbf393b77aa",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "4695430e8132420bf8de94da3eb36a6cf35fde6b",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "0309ebbc570000ea0df11c06b69798e5860c5f6f",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            },
            {
              "lessThan": "a39789f211b8a4125f0c70e05b30cf715f4f187d",
              "status": "affected",
              "version": "6db6f0eae6052b70885562e1733896647ec1d807",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bridge/br_multicast.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.11"
            },
            {
              "lessThan": "4.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.151",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.103",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.44",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.8",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: stop fast-leave after deleting a port group\n\nbr_multicast_leave_group() iterates mp-\u003eports with pp = \u0026p-\u003enext in\nits fast-leave path. After br_multicast_del_pg() removes p,\ncontinuing the loop advances pp through the deleted entry.\n\nIf multicast-to-unicast was enabled, the bridge can hold multiple port\ngroups for the same port and group with different source MAC\naddresses. Once multicast-to-unicast is disabled,\nbr_port_group_equal() matches those entries by port only. A fast leave\ncan then delete one entry and continue from its stale next pointer,\nleaving mp-\u003eports pointing at a deleted port group.\n\nFast leave only needs to remove one matching port group. Break after\nbr_multicast_del_pg() so the loop stops before dereferencing the\nremoved entry."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is reached when the bridge network stack processes attacker-supplied IGMP/MLD Leave packets received on a bridge port (br_handle_frame_finish -\u003e br_multicast_rcv -\u003e br_ip4/ip6_multicast_leave_group -\u003e br_multicast_leave_group), requiring no local syscall access.\nAC:L - Once a bridge has IGMP snooping, fast-leave, and leftover duplicate port groups (common on WiFi APs that used multicast-to-unicast), an attacker can reliably trigger the bug by sending IGMP/MLD joins then a Leave; no uncontrollable race or rare timing is required.\nPR:N - No privileges or authentication are required on the target; any host on an attached bridge port can inject IGMP/MLD Leave packets that are processed and reach the vulnerable fast-leave deletion loop.\nUI:N - Exploitation requires only attacker-sent multicast control packets; no victim user action such as opening files, clicking links, or mounting filesystems is needed.\nS:U - Impact is kernel heap corruption and use-after-free within the bridge/multicast subsystem on the same host; it does not cross a VM/hypervisor or IOMMU security boundary by itself.\nC:H - Deleting a port group then continuing the list walk dereferences freed net_bridge_port_group memory and can leave mp-\u003eports dangling, giving a use-after-free read primitive exploitable for arbitrary kernel memory disclosure.\nI:H - Corrupting the mp-\u003eports linked list via stale next pointers after br_multicast_del_pg() enables attacker-influenced kernel heap corruption that can be developed into arbitrary write and privilege escalation.\nA:H - The use-after-free and corrupted multicast database pointers cause kernel oops/panics when subsequent bridge multicast forwarding or MDB operations traverse the broken port-group list, enabling repeatable denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:47:40.725Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/159ad90cb929c033308bb39a2c5f8fbf393b77aa"
        },
        {
          "url": "https://git.kernel.org/stable/c/4695430e8132420bf8de94da3eb36a6cf35fde6b"
        },
        {
          "url": "https://git.kernel.org/stable/c/0309ebbc570000ea0df11c06b69798e5860c5f6f"
        },
        {
          "url": "https://git.kernel.org/stable/c/4c57056ca6aace2e9f94ae9298bf49ef6b0c95e4"
        },
        {
          "url": "https://git.kernel.org/stable/c/a39789f211b8a4125f0c70e05b30cf715f4f187d"
        }
      ],
      "title": "net: bridge: stop fast-leave after deleting a port group",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74480",
    "datePublished": "2026-08-15T12:27:13.803Z",
    "dateReserved": "2026-08-15T05:44:03.904Z",
    "dateUpdated": "2026-08-17T05:47:40.725Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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FKIE_CVE-2026-74480

CVE-2026-74480 (GCVE-0-2026-74480)

Tags

Sightings

Nomenclature