{"id":"CVE-2026-63438","published":"2026-11-06T21:17:09.770","lastModified":"2026-11-10T20:19:33.583","description":"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.","cvssScore":9.8,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwes":["CWE-287"],"vendors":[],"products":[],"references":[{"url":"https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8","tags":[]},{"url":"https://github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927c","tags":[]},{"url":"https://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de","tags":[]},{"url":"https://github.com/Bubka/2FAuth/releases/tag/v8.0.0","tags":[]},{"url":"https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24","tags":[]},{"url":"https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24","tags":[]}],"exploitRefs":[{"url":"https://github.com/Bubka/2FAuth/commit/43873cbfba445926c7008b4291eeee67752af9e8","tags":[]},{"url":"https://github.com/Bubka/2FAuth/commit/8a4c395cac97f8b70b4a822639a6ad8a816f927c","tags":[]},{"url":"https://github.com/Bubka/2FAuth/commit/d9e58ac4a63fbd8a073e423567881c81a87915de","tags":[]},{"url":"https://github.com/Bubka/2FAuth/releases/tag/v8.0.0","tags":[]},{"url":"https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24","tags":[]},{"url":"https://github.com/Bubka/2FAuth/security/advisories/GHSA-r9xx-45m8-mw24","tags":[]}],"hasPoc":true,"ai":{"summary":"The flaw allows unauthenticated attackers to create or impersonate administrator accounts in 2FAuth by exploiting improper validation of reverse proxy authentication headers, leading to full system compromise including access to 2FA secrets.","exploitability":"Exploitation requires no authentication and can be performed remotely against a fresh or existing instance where AUTHENTICATION_GUARD=reverse-proxy-guard is enabled and the server does not enforce trusted proxy checks.","blast_radius":"Successful exploitation grants full administrative control, enabling theft of 2FA secrets, account takeover, and potential lateral movement within the protected infrastructure.","remediation":"Upgrade to 2FAuth version 8.0.0 or later, which fixes the vulnerability by properly validating reverse proxy authentication headers.","detection":"Look for unexpected creation of new user accounts with administrative privileges in application logs, especially when accompanied by requests containing REMOTE_USER and mail headers from untrusted IP ranges or without prior successful authentication events.","tags":["auth-bypass","privilege-escalation","web-app","reverse-proxy","2fa"],"model":"garnet-coder","analyzedAt":"2026-11-07T09:54:33.207Z"}}