CVE-2026-39831

critical

Published 2026-05-22 · Modified 2026-05-27

CVSS v3

9.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v2

—

VIR risk

9.1

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.

Predictions

Exploit likelihood

94%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2026-39831.html

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2026-39831

OS impact

OS	Version	Status	Fixed in
debian	bookworm	affected
debian	bullseye	affected
debian	forky	affected
debian	sid	fixed	`1:0.52.0-1`
debian	trixie	affected
sles		affected

Package impact

Ecosystem	Package	Vulnerable	Fixed
Go	golang.org/x/crypto	`<0.52.0`	`0.52.0`

References

Verify integrity in audit chain (admin only). AS-IS.