2FAuth: Reverse Proxy Guard Auto-Creates Users With Admin Promotion From Unauthenticated Header Value

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63438
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-06 21:17:09 UTC
Updated2026-11-12 22:18:51 UTC
Description2FAuth 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

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

EPSS: 0.005050000 probability, percentile 0.435020000 (date 2026-11-10)

Problem Types: CWE-287 | CWE-287 CWE-287: Improper Authentication

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Bubka 2FAuth affected < 8.0.0 Not specified

References

ReferenceSourceLinkTags
github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927c [email protected] github.com
github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de [email protected] github.com
github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8 [email protected] github.com
github.com/Bubka/2FAuth/releases/tag/v8.0.0 [email protected] github.com
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