CVE-2026-39831

CRITICAL

Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh

Title source: cna

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.

References (4)

Core 4

Core References

https://go.dev/issue/79566

https://groups.google.com/g/golang-announce/c/a082jnz-LvI

https://go.dev/cl/781662

https://pkg.go.dev/vuln/GO-2026-5019

Scores

CVSS v3 9.1

EPSS 0.0031

EPSS Percentile 22.4%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact total

Details

CWE

CWE-862

Status published

Products (2)

golang/crypto < 0.52.0

golang.org/x/crypto/golang.org/x/crypto/ssh < 0.52.0

Published May 22, 2026

Tracked Since May 22, 2026