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CVE-2026-39831— Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh

AI Predicted 8.8 Difficulty: Moderate EPSS 0.02% · P7

Possible ATT&CK Techniques 1AI

T1110.004 · Credential Stuffing

Affected Version Matrix 1

VendorProductVersion RangeStatus
golang.org/x/cryptogolang.org/x/crypto/ssh< 0.52.0affected
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I. Basic Information for CVE-2026-39831

Vulnerability Information
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Vulnerability Title
Invoking bypass of FIDO/U2F security keys physical interaction in golang.org/x/crypto/ssh
Source: NVD (National Vulnerability Database)
Vulnerability 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 (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
golang.org/x/cryptogolang.org/x/crypto/ssh 0 ~ 0.52.0 -

II. Public POCs for CVE-2026-39831

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III. Intelligence Information for CVE-2026-39831

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Patches & Fixes for CVE-2026-39831 (1)

Vendor Advisories for CVE-2026-39831 (2)

Other References for CVE-2026-39831 (1)

Same Patch Batch · golang.org/x/crypto · 2026-05-22 · 13 CVEs total

CVE-2026-42508Invoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts
CVE-2026-39829Invoking pathological RSA/DSA parameters may cause DoS in golang.org/x/crypto/ssh
CVE-2026-39835Invoking server panic during CheckHostKey/Authenticate in golang.org/x/crypto/ssh
CVE-2026-39833Invoking key constraints not enforced in golang.org/x/crypto/ssh/agent
CVE-2026-39834Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh
CVE-2026-39830Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/
CVE-2026-39828Invoking bypass of certificate restrictions in golang.org/x/crypto/ssh
CVE-2026-39827Invoking memory leak when rejecting channels can lead to DoS in golang.org/x/crypto/ssh
CVE-2026-39832Invoking agent constraints dropped when forwarding keys in golang.org/x/crypto/ssh/agent
CVE-2026-46597Invoking byte arithmetic causes underflow and panic in golang.org/x/crypto/ssh
CVE-2026-46598Invoking pathological inputs can lead to client panic in golang.org/x/crypto/ssh/agent
CVE-2026-46595Invoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x/crypto/ss

IV. Related Vulnerabilities

Same product: golang.org/x/crypto/ssh
Same vendor: golang.org/x/crypto

V. Comments for CVE-2026-39831

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