CVE-2026-63438
2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header Value
2FAuth is a web app to manage Two-Factor Authentication (2FA) accounts and generate their security codes. Prior to 8.0.0, when AUTHENTICATION_GUARD=reverse-proxy-guard accepts authentication headers from a client that did not pass through a trusted proxy, RemoteUserProvider::retrieveById() creates an account for an unknown REMOTE_USER, promotes the first created account to administrator, and synchronizes the account email from the configured mail header. An unauthenticated remote client can therefore create an administrator on a fresh instance or impersonate and redirect email for a known account, exposing 2FA secrets and administrative functions. This issue is fixed in version 8.0.0.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| 2FAuth Bubka |
< 8.0.0 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 9.8 critical |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8CNA: GitHub_M · x_refsource_MISC
- https://github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927cCNA: GitHub_M · x_refsource_MISC
- https://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915deCNA: GitHub_M · x_refsource_MISC
- https://github.com/Bubka/2FAuth/releases/tag/v8.0.0CNA: GitHub_M · x_refsource_MISC
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