Go to homepageCyberStrike

Menu

Star on GitHub · 3.2k
Sign inDownload

CVE-2026-39831

9.1 · CRITICAL

The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) did not check the User Presence flag.

Published May 22, 2026CWE-862EPSS 0.49%

Overview

CVE-2026-39831 is a critical-severity vulnerability. It was published on May 22, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgo.dev/cl/781662Refgo.dev/issue/79566Refgroups.google.com/g/golang-announce/c/a082jnz-LvIRefpkg.go.dev/vuln/GO-2026-5019

How CyberStrike helps

Frequently asked questions

What is CVE-2026-39831?

CVE-2026-39831 is a critical-severity vulnerability. It was published on May 22, 2026 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-39831?

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-39831?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-39831?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-39831 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

Related CRITICAL CVEs from 2026

View all
Browse by year2026202520242023202220212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999