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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
NVD MITRE
EPSS Score
0.4%
Top 65.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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

AV:NAC:LPR:NUI:NS:UC:HI:HA:N
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

golang
oss-project·US
crypto
OSS Libraries
golang.org/x/crypto
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
View detailed technique mapping

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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