CVE-2026-39831

critical · 9.1

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.

9.1

CVSS

0.4%

EPSS (exploit prob.)

36th

EPSS percentile

2026-05-22

Published

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

Weaknesses

CWE-862

Affected products

Vendor	Product	Affected versions
golang	crypto	< 0.52.0

Check a specific version with /api/v1/cve/match.

References

https://go.dev/cl/781662
https://go.dev/issue/79566
https://groups.google.com/g/golang-announce/c/a082jnz-LvI
https://pkg.go.dev/vuln/GO-2026-5019

Query this programmatically:

curl https://evil-db.io/api/v1/cve/CVE-2026-39831