CVE-2026-39831

Published May 22, 2026

Last updated 2 months ago

CVSS critical 9.1
SSH
Port (22)

Overview

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.
Source
security@golang.org
NVD status
Analyzed
Products
crypto

Risk scores

CVSS 3.1

Type
Secondary
Base score
9.1
Impact score
5.2
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Severity
CRITICAL

Weaknesses

nvd@nist.gov
CWE-862

Social media

Hype score
Not currently trending

Configurations

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References

Sources include official advisories and independent security research.