CVE-2026-39831
Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh
- State
- Published
- Severity
- 9.1 Critical
- Published
- May 22, 2026
- Updated
- May 22, 2026
- Reserved
- Apr 7, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N | CISA-ADP |
Weaknesses
The record names no weakness.
Affected Products
| Product | Versions |
|---|---|
golang.org/x/crypto/sshgolang.org/x/crypto |
|
References
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