critical9.1
CVE-2026-39831
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.
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | golang.org/x/crypto | < 0.52.0 | 0.52.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Golang | Crypto | before 0.52.0 |