CVE-2026-46419Network attack vector

User impersonation via failed credential-owner cross-check

Published May 14, 2026 · Updated May 14, 2026

Authentication bypass in Yubico webauthn-server-core 2.8.0 before 2.8.2 allows remote authenticated users to impersonate users. FinishAssertionSteps accepts a valid assertion without cross-checking its verified credential handle against the requested username when the initial user-handle lookup is empty. The attacker needs an existing WebAuthn credential and a known target username without an associated handle in a username-based second-factor deployment.

CVSS severity7.5
High
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Yubico webauthn-server-core 2.8.0 before 2.8.2 allows remote authenticated users to impersonate users. FinishAssertionSteps accepts a valid assertion without cross-checking its verified credential handle against the requested username when the initial user-handle lookup is empty. The attacker needs an existing WebAuthn credential and a known target username without an associated handle in a username-based second-factor deployment.

The record

CVE
CVE-2026-46419
Published
May 14, 2026
Updated
May 14, 2026
Vendor
Yubico
Product
webauthn-server-core
Classifications
CWE-253, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 14, 2026CVE publishedPublication date reported by the CVE source.
  2. May 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.8.0 <2.8.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Yubico · webauthn-server-coreversion=2.8.0 <2.8.2

Published CVSS scores

7.5MITRECVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-253Incorrect Check of Function Return Value
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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