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CVE

CVE-2026-39831

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

CVE-2026-39831

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

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.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
C
H
U
0
-
C
H
U
-

Related Resources

No items found.

References

https://go.dev/issue/79566, https://groups.google.com/g/golang-announce/c/a082jnz-LvI, https://go.dev/cl/781662

Severity

9.1

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
9.1
EPSS Probability
0.00033%
EPSS Percentile
0.0998%
Introduced Version
0
Fix Available
0.52.0

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