Vulnerability-Lookup

GHSA-478P-QCHQ-Q398

Vulnerability from github – Published: 2026-05-27 15:33 – Updated: 2026-05-27 15:33

Details

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

ovpn: tcp - don't deref NULL sk_socket member after tcp_close()

When deleting a peer in case of keepalive expiration, the peer is removed from the OpenVPN hashtable and is temporary inserted in a "release list" for further processing.

This happens in: ovpn_peer_keepalive_work() unlock_ovpn(release_list)

This processing includes detaching from the socket being used to talk to this peer, by restoring its original proto and socket ops/callbacks.

In case of TCP it may happen that, while the peer is sitting in the release list, userspace decides to close the socket. This will result in a concurrent execution of:

tcp_close(sk) __tcp_close(sk) sock_orphan(sk) sk_set_socket(sk, NULL)

The last function call will set sk->sk_socket to NULL.

When the releasing routine is resumed, ovpn_tcp_socket_detach() will attempt to dereference sk->sk_socket to restore its original ops member. This operation will crash due to sk->sk_socket being NULL.

Fix this race condition by testing-and-accessing sk->sk_socket atomically under sk->sk_callback_lock.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-45918"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T14:17:06Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\novpn: tcp - don\u0027t deref NULL sk_socket member after tcp_close()\n\nWhen deleting a peer in case of keepalive expiration, the peer is\nremoved from the OpenVPN hashtable and is temporary inserted in a\n\"release list\" for further processing.\n\nThis happens in:\novpn_peer_keepalive_work()\n  unlock_ovpn(release_list)\n\nThis processing includes detaching from the socket being used to\ntalk to this peer, by restoring its original proto and socket\nops/callbacks.\n\nIn case of TCP it may happen that, while the peer is sitting in\nthe release list, userspace decides to close the socket.\nThis will result in a concurrent execution of:\n\ntcp_close(sk)\n  __tcp_close(sk)\n    sock_orphan(sk)\n      sk_set_socket(sk, NULL)\n\nThe last function call will set sk-\u003esk_socket to NULL.\n\nWhen the releasing routine is resumed, ovpn_tcp_socket_detach()\nwill attempt to dereference sk-\u003esk_socket to restore its original\nops member. This operation will crash due to sk-\u003esk_socket being NULL.\n\nFix this race condition by testing-and-accessing\nsk-\u003esk_socket atomically under sk-\u003esk_callback_lock.",
  "id": "GHSA-478p-qchq-q398",
  "modified": "2026-05-27T15:33:16Z",
  "published": "2026-05-27T15:33:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45918"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/94560267d6c41b1ff3fafbab726e3f8a55a6af34"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b9142cf4e066c825ec68752a7dcaceda700bbe26"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f998b2c4bec487063a586695159f9a1856e81c56"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-45918 (GCVE-0-2026-45918)

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

Title

ovpn: tcp - don't deref NULL sk_socket member after tcp_close()

Summary

In the Linux kernel, the following vulnerability has been resolved: ovpn: tcp - don't deref NULL sk_socket member after tcp_close() When deleting a peer in case of keepalive expiration, the peer is removed from the OpenVPN hashtable and is temporary inserted in a "release list" for further processing. This happens in: ovpn_peer_keepalive_work() unlock_ovpn(release_list) This processing includes detaching from the socket being used to talk to this peer, by restoring its original proto and socket ops/callbacks. In case of TCP it may happen that, while the peer is sitting in the release list, userspace decides to close the socket. This will result in a concurrent execution of: tcp_close(sk) __tcp_close(sk) sock_orphan(sk) sk_set_socket(sk, NULL) The last function call will set sk->sk_socket to NULL. When the releasing routine is resumed, ovpn_tcp_socket_detach() will attempt to dereference sk->sk_socket to restore its original ops member. This operation will crash due to sk->sk_socket being NULL. Fix this race condition by testing-and-accessing sk->sk_socket atomically under sk->sk_callback_lock.

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/f998b2c4bec487063…
https://git.kernel.org/stable/c/b9142cf4e066c825e…
https://git.kernel.org/stable/c/94560267d6c41b1ff…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 11851cbd60ea1e5abbd97619d69845ead99303d6 , < f998b2c4bec487063a586695159f9a1856e81c56 (git) Affected: 11851cbd60ea1e5abbd97619d69845ead99303d6 , < b9142cf4e066c825ec68752a7dcaceda700bbe26 (git) Affected: 11851cbd60ea1e5abbd97619d69845ead99303d6 , < 94560267d6c41b1ff3fafbab726e3f8a55a6af34 (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.14 , ≤ 6.18.* (semver) Unaffected: 6.19.4 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ovpn/tcp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f998b2c4bec487063a586695159f9a1856e81c56",
              "status": "affected",
              "version": "11851cbd60ea1e5abbd97619d69845ead99303d6",
              "versionType": "git"
            },
            {
              "lessThan": "b9142cf4e066c825ec68752a7dcaceda700bbe26",
              "status": "affected",
              "version": "11851cbd60ea1e5abbd97619d69845ead99303d6",
              "versionType": "git"
            },
            {
              "lessThan": "94560267d6c41b1ff3fafbab726e3f8a55a6af34",
              "status": "affected",
              "version": "11851cbd60ea1e5abbd97619d69845ead99303d6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ovpn/tcp.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.4",
              "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": "6.18.14",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.4",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\novpn: tcp - don\u0027t deref NULL sk_socket member after tcp_close()\n\nWhen deleting a peer in case of keepalive expiration, the peer is\nremoved from the OpenVPN hashtable and is temporary inserted in a\n\"release list\" for further processing.\n\nThis happens in:\novpn_peer_keepalive_work()\n  unlock_ovpn(release_list)\n\nThis processing includes detaching from the socket being used to\ntalk to this peer, by restoring its original proto and socket\nops/callbacks.\n\nIn case of TCP it may happen that, while the peer is sitting in\nthe release list, userspace decides to close the socket.\nThis will result in a concurrent execution of:\n\ntcp_close(sk)\n  __tcp_close(sk)\n    sock_orphan(sk)\n      sk_set_socket(sk, NULL)\n\nThe last function call will set sk-\u003esk_socket to NULL.\n\nWhen the releasing routine is resumed, ovpn_tcp_socket_detach()\nwill attempt to dereference sk-\u003esk_socket to restore its original\nops member. This operation will crash due to sk-\u003esk_socket being NULL.\n\nFix this race condition by testing-and-accessing\nsk-\u003esk_socket atomically under sk-\u003esk_callback_lock."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-27T12:17:34.500Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/f998b2c4bec487063a586695159f9a1856e81c56"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9142cf4e066c825ec68752a7dcaceda700bbe26"
        },
        {
          "url": "https://git.kernel.org/stable/c/94560267d6c41b1ff3fafbab726e3f8a55a6af34"
        }
      ],
      "title": "ovpn: tcp - don\u0027t deref NULL sk_socket member after tcp_close()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45918",
    "datePublished": "2026-05-27T12:17:34.500Z",
    "dateReserved": "2026-05-13T15:03:33.085Z",
    "dateUpdated": "2026-05-27T12:17:34.500Z",
    "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.

Action not permitted

GHSA-478P-QCHQ-Q398

CVE-2026-45918 (GCVE-0-2026-45918)

Tags

Sightings

Nomenclature