CVE-2026-39831

CRITICAL9.1

Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh

Published May 22, 2026

Modified 1 weeks ago

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.

References

WEB

https://go.dev/cl/781662

WEB

https://go.dev/issue/79566

WEB

https://groups.google.com/g/golang-announce/c/a082jnz-LvI

WEB

https://pkg.go.dev/vuln/GO-2026-5019

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-39831

CVSS Analysis