{"schema_version":"1.3.1","id":"GO-2026-5019","modified":"2026-05-22T02:08:34Z","published":"2026-05-22T02:08:34Z","aliases":["CVE-2026-39831"],"summary":"Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh","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.","affected":[{"package":{"name":"golang.org/x/crypto","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.52.0"}]}],"ecosystem_specific":{"imports":[{"path":"golang.org/x/crypto/ssh","symbols":["CertChecker.Authenticate","CertChecker.CheckCert","CertChecker.CheckHostKey","Certificate.Verify","Dial","NewClientConn","NewServerConn","connection.serverAuthenticate","skECDSAPublicKey.Verify","skEd25519PublicKey.Verify"]}]}}],"references":[{"type":"REPORT","url":"https://go.dev/issue/79566"},{"type":"WEB","url":"https://groups.google.com/g/golang-announce/c/a082jnz-LvI"},{"type":"FIX","url":"https://go.dev/cl/781662"}],"credits":[{"name":"NCC Group Cryptography Services, sponsored by Teleport"}],"database_specific":{"url":"https://pkg.go.dev/vuln/GO-2026-5019","review_status":"REVIEWED"}}