Bubka 2FAuth up to 7.x RemoteUserProvider retrieveById access control

Summaryinfo

A vulnerability was found in Bubka 2FAuth up to 7.x. It has been rated as critical. The impacted element is the function RemoteUserProvider::retrieveById of the component RemoteUserProvider. The manipulation leads to access control. This vulnerability is documented as CVE-2026-63438. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Bubka 2FAuth up to 7.x and classified as critical. This issue affects the function RemoteUserProvider::retrieveById of the component RemoteUserProvider. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-63438 since 07/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading to version 8.0.0 eliminates this vulnerability.

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Productinfo

Vendor

• Bubka

Name

• 2FAuth

Version

• 7.x

Website

• Product: https://github.com/Bubka/2FAuth/

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CPE 2.2info

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