Vulnerability-Lookup

CVE-2026-64523 (GCVE-0-2026-64523)

Vulnerability from cvelistv5 – Published: 2026-07-25 09:20 – Updated: 2026-07-25 09:20

Title

net/handshake: Take a long-lived file reference at submit

Summary

In the Linux kernel, the following vulnerability has been resolved: net/handshake: Take a long-lived file reference at submit handshake_nl_accept_doit() needs the file pointer backing req->hr_sk->sk_socket to survive the window between handshake_req_next() and the subsequent FD_PREPARE() and get_file(). The submit-side sock_hold() does not provide that. sk_refcnt keeps struct sock alive, but struct socket is owned by sock->file: when the consumer fputs the last file reference, sock_release() tears the socket down regardless of any sock_hold. Add an hr_file pointer to struct handshake_req and acquire an explicit reference on sock->file during handshake_req_submit(). handshake_complete() and handshake_req_cancel() release the reference on the completion-bit-winning path. The submit error path must also release the file reference, but after rhashtable insertion a concurrent handshake_req_cancel() can discover the request and race the error path. Gate the error-path cleanup -- sk_destruct restoration, fput, and request destruction -- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same serialization handshake_complete() and handshake_req_cancel() already use. When cancel has already claimed ownership, the submit error path returns without touching the request; socket teardown handles final destruction. The accept-side dereferences are not yet retargeted; that change comes in the next patch.

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/685b10dd0e32c7782…
https://git.kernel.org/stable/c/16eaba5aa89c04eea…
https://git.kernel.org/stable/c/09dba37eee70d0596…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 685b10dd0e32c7782cead16c8cf055c609678583 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 16eaba5aa89c04eea125905bb8f988c1897f4f29 (git) Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 09dba37eee70d0596e26645015f1aa95a9848e9d (git) Affected: 0 , < 6.12.93 (semver) Affected: 0 , < 7.0.12 (semver)
Linux	Linux	Unaffected: 6.12.93 , ≤ 6.12.* (semver) Unaffected: 7.0.12 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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JSON

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{
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            "net/handshake/handshake.h",
            "net/handshake/netlink.c",
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          ],
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          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
            },
            {
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              "versionType": "git"
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              "status": "affected",
              "version": "0",
              "versionType": "semver"
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          "product": "Linux",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: Take a long-lived file reference at submit\n\nhandshake_nl_accept_doit() needs the file pointer backing\nreq-\u003ehr_sk-\u003esk_socket to survive the window between\nhandshake_req_next() and the subsequent FD_PREPARE() and get_file().\nThe submit-side sock_hold() does not provide that.  sk_refcnt keeps\nstruct sock alive, but struct socket is owned by sock-\u003efile: when\nthe consumer fputs the last file reference, sock_release() tears\nthe socket down regardless of any sock_hold.\n\nAdd an hr_file pointer to struct handshake_req and acquire an\nexplicit reference on sock-\u003efile during handshake_req_submit().\nhandshake_complete() and handshake_req_cancel() release the\nreference on the completion-bit-winning path.\n\nThe submit error path must also release the file reference, but\nafter rhashtable insertion a concurrent handshake_req_cancel() can\ndiscover the request and race the error path.  Gate the error-path\ncleanup -- sk_destruct restoration, fput, and request destruction\n-- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same\nserialization handshake_complete() and handshake_req_cancel()\nalready use.  When cancel has already claimed ownership, the submit\nerror path returns without touching the request; socket teardown\nhandles final destruction.\n\nThe accept-side dereferences are not yet retargeted; that change\ncomes in the next patch."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-25T09:20:47.606Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
        {
          "url": "https://git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d"
        }
      ],
      "title": "net/handshake: Take a long-lived file reference at submit",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    "cveId": "CVE-2026-64523",
    "datePublished": "2026-07-25T09:20:47.606Z",
    "dateReserved": "2026-07-19T15:36:31.794Z",
    "dateUpdated": "2026-07-25T09:20:47.606Z",
    "state": "PUBLISHED"
  },
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      "date": "2026-07-25",
      "epss": "0.00206",
      "percentile": "0.10863"
    },
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  }
}

GHSA-FC48-5G6G-X546

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-25 12:31

Details

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

net/handshake: Take a long-lived file reference at submit

handshake_nl_accept_doit() needs the file pointer backing req->hr_sk->sk_socket to survive the window between handshake_req_next() and the subsequent FD_PREPARE() and get_file(). The submit-side sock_hold() does not provide that. sk_refcnt keeps struct sock alive, but struct socket is owned by sock->file: when the consumer fputs the last file reference, sock_release() tears the socket down regardless of any sock_hold.

Add an hr_file pointer to struct handshake_req and acquire an explicit reference on sock->file during handshake_req_submit(). handshake_complete() and handshake_req_cancel() release the reference on the completion-bit-winning path.

The submit error path must also release the file reference, but after rhashtable insertion a concurrent handshake_req_cancel() can discover the request and race the error path. Gate the error-path cleanup -- sk_destruct restoration, fput, and request destruction -- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same serialization handshake_complete() and handshake_req_cancel() already use. When cancel has already claimed ownership, the submit error path returns without touching the request; socket teardown handles final destruction.

The accept-side dereferences are not yet retargeted; that change comes in the next patch.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-64523"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:38Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: Take a long-lived file reference at submit\n\nhandshake_nl_accept_doit() needs the file pointer backing\nreq-\u003ehr_sk-\u003esk_socket to survive the window between\nhandshake_req_next() and the subsequent FD_PREPARE() and get_file().\nThe submit-side sock_hold() does not provide that.  sk_refcnt keeps\nstruct sock alive, but struct socket is owned by sock-\u003efile: when\nthe consumer fputs the last file reference, sock_release() tears\nthe socket down regardless of any sock_hold.\n\nAdd an hr_file pointer to struct handshake_req and acquire an\nexplicit reference on sock-\u003efile during handshake_req_submit().\nhandshake_complete() and handshake_req_cancel() release the\nreference on the completion-bit-winning path.\n\nThe submit error path must also release the file reference, but\nafter rhashtable insertion a concurrent handshake_req_cancel() can\ndiscover the request and race the error path.  Gate the error-path\ncleanup -- sk_destruct restoration, fput, and request destruction\n-- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same\nserialization handshake_complete() and handshake_req_cancel()\nalready use.  When cancel has already claimed ownership, the submit\nerror path returns without touching the request; socket teardown\nhandles final destruction.\n\nThe accept-side dereferences are not yet retargeted; that change\ncomes in the next patch.",
  "id": "GHSA-fc48-5g6g-x546",
  "modified": "2026-07-25T12:31:39Z",
  "published": "2026-07-25T12:31:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64523"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/16eaba5aa89c04eea125905bb8f988c1897f4f29"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/685b10dd0e32c7782cead16c8cf055c609678583"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

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.

Action not permitted

CVE-2026-64523 (GCVE-0-2026-64523)

GHSA-FC48-5G6G-X546

Tags

Sightings

Nomenclature