CVE-2026-73313Public exploitNetwork attack vector

MFA bypass via cross-user passkey acceptance

Published Sep 8, 2026 · Updated Sep 9, 2026

Authentication bypass in XenForo before 2.3.13 allows remote authenticated users to complete another user's login through passkey TFA. The WebAuthn assertion path looks up the submitted credential globally but never verifies that it belongs to the account with the pending login. Exploitation requires the target's password and an attacker-controlled registered passkey, and it bypasses MFA on forum and ACP logins.

CVSS severity7.6
High
EPSS probability0.39%
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 XenForo before 2.3.13 allows remote authenticated users to complete another user's login through passkey TFA. The WebAuthn assertion path looks up the submitted credential globally but never verifies that it belongs to the account with the pending login. Exploitation requires the target's password and an attacker-controlled registered passkey, and it bypasses MFA on forum and ACP logins.

The record

CVE
CVE-2026-73313
Published
Sep 8, 2026
Updated
Sep 9, 2026
Vendor
XenForo Ltd.
Product
XenForo
Classifications
CWE-863, T1078
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <2.3.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

XenForo Ltd. · XenForoversion=0 <2.3.13

Published CVSS scores

7.6VulnCheckCVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
6.8VulnCheckCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1078Valid Accounts

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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