What is CVE-2026-39831?

CVE-2026-39831 is a critical-severity vulnerability in Golang Crypto, classified under Missing Authorization. CVSS score: 9.1/10. Published 2026-05-22.

How severe is CVE-2026-39831?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Auth bypass in Golang Crypto

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. Signatures generated without physical touch were accepted, allowing unattended use o…

Vulnerability class: Broken Access Control

EPSS: 0.000 (10.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Golang Crypto
Golang.org/x/crypto Golang.org/x/crypto/ssh — versions 0

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

security@golang.org (Issue Tracking)
security@golang.org (Mailing List)
security@golang.org (Issue Tracking)
security@golang.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-39831?: CVE-2026-39831 is a critical-severity vulnerability in Golang Crypto, classified under Missing Authorization. CVSS score: 9.1/10. Published 2026-05-22.
How severe is CVE-2026-39831?: Critical severity. CVSS v3 base score is 9.1 out of 10.