CVE-2026-39831

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

Critical · published May 22, 2026

CVSS v3.1
9.1
EPSS
0%
Percentile
41.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
9.1 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00487 · 41.0th percentile
Published
2026-05-22T02:31Z
EPSS history
Timeline
  • 22 MAY 02:31Z
    Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh
    cvelistv5