x-crypto up to 0.51.x FIDO/U2F Verify authentication spoofing

Summaryinfo

A vulnerability, which was classified as critical, was found in x-crypto up to 0.51.x. Affected is the function Verify of the component FIDO/U2F. Executing a manipulation can lead to authentication spoofing. This vulnerability is tracked as CVE-2026-39831. The physical device can be targeted for the attack. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in x-crypto up to 0.51.x. This vulnerability affects the function Verify of the component FIDO/U2F. The manipulation with an unknown input leads to a authentication spoofing vulnerability. The CWE definition for the vulnerability is CWE-290. This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at go.dev. This vulnerability was named CVE-2026-39831 since 04/07/2026. The exploitation appears to be easy. Local access is required to approach this attack. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 316571 (Linux Distros Unpatched Vulnerability : CVE-2026-39831), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.52.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (316571), EUVD (EUVD-2026-31395) and CERT Bund (WID-SEC-2026-1653). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Amazon Linux 2
• Red Hat Enterprise Linux
• Fedora Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• RESF Rocky Linux
• IBM MQ
• Golang Go
• SUSE openSUSE
• Red Hat OpenShift

Productinfo

Name

• x-crypto

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18
• 0.19
• 0.20
• 0.21
• 0.22
• 0.23
• 0.24
• 0.25
• 0.26
• 0.27
• 0.28
• 0.29
• 0.30
• 0.31
• 0.32
• 0.33
• 0.34
• 0.35
• 0.36
• 0.37
• 0.38
• 0.39
• 0.40
• 0.41
• 0.42
• 0.43
• 0.44
• 0.45
• 0.46
• 0.47
• 0.48
• 0.49
• 0.50
• 0.51

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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