CVE-2026-39831

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

Published: May 22, 2026Updated: Jul 23, 2026 Sources: CVE List NVDCWE-862

9.1CRITICAL

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.

No summary for this CVE yet.

CVSS Vector Breakdown

Exploitability

AV:NAttack Vector

Network

AC:LAttack Complexity

Low

PR:NPrivileges Required

None

UI:NUser Interaction

None

Scope

S:UScope

Unchanged

Impact

C:HConfidentiality

High

I:HIntegrity

High

A:NAvailability

None

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Weaknesses

CWE-862

Affected Products

oss-project·US

oss-projectaka x/crypto, golang x crypto

golang.org/x/crypto/sshLibrary

OSS Libraries / go

Exploitability

Official Patch Available

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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques

Initial Access

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References

https://go.dev/cl/781662

go.dev

https://go.dev/issue/79566

go.dev

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

groups.google.com

and 1 more references View all →

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