GHSA-FC6X-H5H8-WJR3

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33
VLAI
Details

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

handshake: Require admin permission for DONE command

ACCEPT and DONE are the two downcalls of the handshake genl family, both intended for use by the trusted handshake agent (tlshd). ACCEPT already requires GENL_ADMIN_PERM; DONE has no privilege check at all.

The fd-lookup in handshake_nl_done_doit() only confirms that some pending handshake request exists for the supplied sockfd; it does not authenticate the sender. An unprivileged process that guesses or observes a valid sockfd can therefore submit a DONE with HANDSHAKE_A_DONE_STATUS == 0, leaving the kernel consumer to proceed as if the handshake succeeded. A non-zero status on a forged DONE tears down a legitimate in-flight handshake before tlshd can report its real result.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-74270"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:26Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhandshake: Require admin permission for DONE command\n\nACCEPT and DONE are the two downcalls of the handshake genl\nfamily, both intended for use by the trusted handshake agent\n(tlshd). ACCEPT already requires GENL_ADMIN_PERM; DONE has\nno privilege check at all.\n\nThe fd-lookup in handshake_nl_done_doit() only confirms that\nsome pending handshake request exists for the supplied sockfd;\nit does not authenticate the sender. An unprivileged process\nthat guesses or observes a valid sockfd can therefore submit\na DONE with HANDSHAKE_A_DONE_STATUS == 0, leaving the kernel\nconsumer to proceed as if the handshake succeeded. A non-zero\nstatus on a forged DONE tears down a legitimate in-flight\nhandshake before tlshd can report its real result.",
  "id": "GHSA-fc6x-h5h8-wjr3",
  "modified": "2026-08-17T06:33:35Z",
  "published": "2026-08-15T06:32:27Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74270"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/25fb53e43ec006ac69b9e825a7e8a11d63a6083e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4dafc411948469277b276724c3b2b4408c02c04c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/67cec2f1eb9e58719d622e92e2278ceda72dbd85"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/81246a65303d9635266b1334490142caaf86a11f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b6557f912509abe8e70223373dd7a44d1d4a0d6c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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