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

OpenSSH · CVE-2026-39831
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What is it?

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.

Evidence

No coverage recorded yet.

Exploitation

  • Public proof of concept
  • Exploited in the wild
  • Listed as known exploited
CVSS
9.1
EPSS
0.5%
First seen
1 d ago
Status
corroborated

All OpenSSH vulnerabilities