FKIE_CVE-2026-39831

Vulnerability from fkie_nvd - Published: 2026-05-22 04:16 - Updated: 2026-06-17 10:42
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."
    }
  ],
  "id": "CVE-2026-39831",
  "lastModified": "2026-06-17T10:42:39.630",
  "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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