CVE-2026-31504 (GCVE-0-2026-31504)
Vulnerability from cvelistv5
Published
2026-04-22 13:54
Modified
2026-04-27 14:03
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
References
Impacted products
Vendor Product Version
Linux Linux Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
Version: ce06b03e60fc19c680d1bf873e779bf11c2fc518
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/packet/af_packet.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ee642b1962caa9aa231c01abbd58bc453ae6b66e",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "42cfd7898eeed290c9fb73f732af1f7d6b0a703e",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "1b4c03f8892d955385c202009af7485364731bb9",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "654386baef228c2992dbf604c819e4c7c35fc71b",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "75fe6db23705a1d55160081f7b37db9665b1880b",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "ceccbfc6de720ad633519a226715989cfb065af1",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            },
            {
              "lessThan": "42156f93d123436f2a27c468f18c966b7e5db796",
              "status": "affected",
              "version": "ce06b03e60fc19c680d1bf873e779bf11c2fc518",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/packet/af_packet.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.1"
            },
            {
              "lessThan": "3.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.168",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.131",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.80",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.21",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.168",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.131",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.80",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.21",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.11",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "3.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: fix fanout UAF in packet_release() via NETDEV_UP race\n\n`packet_release()` has a race window where `NETDEV_UP` can re-register a\nsocket into a fanout group\u0027s `arr[]` array. The re-registration is not\ncleaned up by `fanout_release()`, leaving a dangling pointer in the fanout\narray.\n`packet_release()` does NOT zero `po-\u003enum` in its `bind_lock` section.\nAfter releasing `bind_lock`, `po-\u003enum` is still non-zero and `po-\u003eifindex`\nstill matches the bound device. A concurrent `packet_notifier(NETDEV_UP)`\nthat already found the socket in `sklist` can re-register the hook.\nFor fanout sockets, this re-registration calls `__fanout_link(sk, po)`\nwhich adds the socket back into `f-\u003earr[]` and increments `f-\u003enum_members`,\nbut does NOT increment `f-\u003esk_ref`.\n\nThe fix sets `po-\u003enum` to zero in `packet_release` while `bind_lock` is\nheld to prevent NETDEV_UP from linking, preventing the race window.\n\nThis bug was found following an additional audit with Claude Code based\non CVE-2025-38617."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-27T14:03:42.262Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ee642b1962caa9aa231c01abbd58bc453ae6b66e"
        },
        {
          "url": "https://git.kernel.org/stable/c/42cfd7898eeed290c9fb73f732af1f7d6b0a703e"
        },
        {
          "url": "https://git.kernel.org/stable/c/1b4c03f8892d955385c202009af7485364731bb9"
        },
        {
          "url": "https://git.kernel.org/stable/c/654386baef228c2992dbf604c819e4c7c35fc71b"
        },
        {
          "url": "https://git.kernel.org/stable/c/75fe6db23705a1d55160081f7b37db9665b1880b"
        },
        {
          "url": "https://git.kernel.org/stable/c/d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6"
        },
        {
          "url": "https://git.kernel.org/stable/c/ceccbfc6de720ad633519a226715989cfb065af1"
        },
        {
          "url": "https://git.kernel.org/stable/c/42156f93d123436f2a27c468f18c966b7e5db796"
        }
      ],
      "title": "net: fix fanout UAF in packet_release() via NETDEV_UP race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31504",
    "datePublished": "2026-04-22T13:54:23.862Z",
    "dateReserved": "2026-03-09T15:48:24.105Z",
    "dateUpdated": "2026-04-27T14:03:42.262Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.