CVE-2026-39831

9.1 CRITICAL

The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) did not check the Us...

Published: 2026-05-22 · Last updated: 2026-06-02

Severity and scoring

CVSS: 9.1 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE: CWE-862

Affected products

Vendor	Product
golang	crypto

Description

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.

Source: NVD

References

[NVD]https://nvd.nist.gov/vuln/detail/CVE-2026-39831
[Other]https://go.dev/cl/781662
[Other]https://go.dev/issue/79566
[Other]https://groups.google.com/g/golang-announce/c/a082jnz-LvI
[Vendor advisory]https://pkg.go.dev/vuln/GO-2026-5019

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