{"id":"CVE-2026-39831","state":"PUBLISHED","title":"Invoking  bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh","description":"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.","publishedAt":"2026-05-22T02:31:27.436Z","updatedAt":"2026-05-22T18:52:08.344Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"CISA-ADP"},"assigner":"Go","products":["golang.org/x/crypto golang.org/x/crypto/ssh"],"affected":[{"vendor":"golang.org/x/crypto","product":"golang.org/x/crypto/ssh","packageName":"golang.org/x/crypto/ssh","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.52.0","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","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"}]}],"references":["https://go.dev/issue/79566","https://groups.google.com/g/golang-announce/c/a082jnz-LvI","https://go.dev/cl/781662","https://pkg.go.dev/vuln/GO-2026-5019"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:50.837Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/39xxx/CVE-2026-39831.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-39831","state":"PUBLISHED","datePublished":"2026-05-22T02:31:27.436Z","dateUpdated":"2026-05-22T18:52:08.344Z","assignerShortName":"Go","assignerOrgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateReserved":"2026-04-07T18:13:03.528Z"},"containers":{"cna":{"title":"Invoking  bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh","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."}],"affected":[{"vendor":"golang.org/x/crypto","product":"golang.org/x/crypto/ssh","packageName":"golang.org/x/crypto/ssh","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.52.0","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","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"}]}],"references":[{"url":"https://go.dev/issue/79566"},{"url":"https://groups.google.com/g/golang-announce/c/a082jnz-LvI"},{"url":"https://go.dev/cl/781662"},{"url":"https://pkg.go.dev/vuln/GO-2026-5019"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-290: Authentication Bypass by Spoofing"}]}],"providerMetadata":{"shortName":"Go","orgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateUpdated":"2026-05-22T02:31:27.436Z"},"credits":[{"lang":"en","value":"NCC Group Cryptography Services, sponsored by Teleport"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":9.1,"attackVector":"NETWORK","baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-05-22T18:51:41.233749Z","id":"CVE-2026-39831","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-22T18:52:08.344Z"}}]}}}