FKIE_CVE-2026-39831

Vulnerability from fkie_nvd - Published: 2026-05-22 04:16 - Updated: 2026-07-23 16:10
Severity
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Summary
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.
References
security@golang.orghttps://go.dev/cl/781662Issue Tracking
security@golang.orghttps://go.dev/issue/79566Issue Tracking
security@golang.orghttps://groups.google.com/g/golang-announce/c/a082jnz-LvIMailing List
security@golang.orghttps://pkg.go.dev/vuln/GO-2026-5019Vendor Advisory
Impacted products
Vendor Product Version
golang crypto *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "golang.org/x/crypto/ssh",
          "product": "golang.org/x/crypto/ssh",
          "programRoutines": [
            {
              "name": "CertChecker.CheckCert"
            },
            {
              "name": "skECDSAPublicKey.Verify"
            },
            {
              "name": "skEd25519PublicKey.Verify"
            },
            {
              "name": "connection.serverAuthenticate"
            },
            {
              "name": "CertChecker.Authenticate"
            },
            {
              "name": "CertChecker.CheckHostKey"
            },
            {
              "name": "Certificate.Verify"
            },
            {
              "name": "Dial"
            },
            {
              "name": "NewClientConn"
            },
            {
              "name": "NewServerConn"
            }
          ],
          "vendor": "golang.org/x/crypto",
          "versions": [
            {
              "lessThan": "0.52.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "security@golang.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*",
              "matchCriteriaId": "D540395B-31B8-4B07-8F79-F5C631BBD5C8",
              "versionEndExcluding": "0.52.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "El m\u00e9todo Verify() para tipos de clave de seguridad FIDO/U2F (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) no verificaba el indicador de Presencia de Usuario. Se aceptaban firmas generadas sin contacto f\u00edsico, lo que permit\u00eda el uso desatendido de una clave de seguridad de hardware. Para restaurar el comportamiento anterior, devuelva una extensi\u00f3n \u0027no-touch-required\u0027 en Permissions.Extensions desde PublicKeyCallback."
    }
  ],
  "id": "CVE-2026-39831",
  "lastModified": "2026-07-23T16:10:00.137",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-39831",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-22T18:51:41.233749Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-22T04:16:22.553",
  "references": [
    {
      "source": "security@golang.org",
      "tags": [
        "Issue Tracking"
      ],
      "url": "https://go.dev/cl/781662"
    },
    {
      "source": "security@golang.org",
      "tags": [
        "Issue Tracking"
      ],
      "url": "https://go.dev/issue/79566"
    },
    {
      "source": "security@golang.org",
      "tags": [
        "Mailing List"
      ],
      "url": "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
    },
    {
      "source": "security@golang.org",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://pkg.go.dev/vuln/GO-2026-5019"
    }
  ],
  "sourceIdentifier": "security@golang.org",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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