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CVE-2026-39831

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

CVSS 9.1 CRITICALEPSS 0.4%
Vexday Risk Score
28Bajo
Decisión SSVC (CISA)
Track
Sin señal de explotación → monitorear
CVSS 9.1EPSS 0.4%KEV nãoPoC Nuclei Metasploit Patch
Ciclo de vida
22 may 2026Publicada en NVD
Recomendación: Monitorear — sin señal de explotación por ahora.
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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