GHSA-89GR-R52H-F8RX

Vulnerability from github – Published: 2026-06-25 22:21 – Updated: 2026-06-25 22:21
VLAI?
Summary
golang.org/x/crypto/ssh: FIDO/U2F security key physical presence check can be bypassed
Details

The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback.

Severity ?
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "golang.org/x/crypto/ssh"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.52.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39831"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-25T22:21:12Z",
    "nvd_published_at": "2026-05-22T04:16:22Z",
    "severity": "CRITICAL"
  },
  "details": "The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a \"no-touch-required\" extension in Permissions.Extensions from PublicKeyCallback.",
  "id": "GHSA-89gr-r52h-f8rx",
  "modified": "2026-06-25T22:21:12Z",
  "published": "2026-06-25T22:21:12Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-39831"
    },
    {
      "type": "PACKAGE",
      "url": "https://cs.opensource.google/go/x/crypto"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/cl/781662"
    },
    {
      "type": "WEB",
      "url": "https://go.dev/issue/79566"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-5019"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": " golang.org/x/crypto/ssh: FIDO/U2F security key physical presence check can be bypassed"
}


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