CVE-2026-39831 — Vulnerability in golang.org/x/crypto — CVE Details

CRITICAL

golang.org/x/crypto: FIDO/U2F security key physical presence check can be bypassed

Published June 25, 2026Updated September 10, 2026Source: osv

Summary

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.

Advisory Timeline

First published June 25, 2026 (109 days ago).
Last revised September 10, 2026 — 76 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Update golang.org/x/crypto to 0.52.0 or later

go get golang.org/x/crypto@v0.52.0

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: go (1).

Package	Ecosystem	Affected	Fixed In
golang.org/x/crypto	go	All versions	0.52.0

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-862
Missing AuthorizationMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.1 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

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

References

Frequently Asked Questions

What is CVE-2026-39831?: golang.org/x/crypto: FIDO/U2F security key physical presence check can be bypassed This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.1/10).
How do I check if my project is affected by CVE-2026-39831?: CVE-2026-39831 affects golang.org/x/crypto. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-39831 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

9.1

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-89gr-r52h-f8rx

GO-2026-5019

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