CVE-2026-39831
CRITICAL9.1EPSS 0.03%Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh
Published: 5/22/2026Modified: 5/29/2026
Description
The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) 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 packages (2)
- Debian/golang-go.cryptofrom 0
- Go/golang.org/x/cryptofrom 0, < 0.52.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |