CVE-2023-49947 in Forgejo
Summary
by MITRE • 12/03/2023
Forgejo before 1.20.5-1 allows 2FA bypass when docker login uses Basic Authentication.
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Analysis
by VulDB Data Team • 03/05/2026
This vulnerability exists in Forgejo versions prior to 1.20.5-1 and represents a critical authentication weakness that enables unauthorized access through a two-factor authentication bypass mechanism. The flaw specifically manifests when users attempt to authenticate via docker login using basic authentication credentials, creating an exploitable pathway that circumvents the intended multi-factor security controls.
The technical implementation of this vulnerability stems from improper authentication flow handling within Forgejo's container registry integration. When docker login operations utilize basic authentication, the system fails to properly validate or enforce two-factor authentication requirements that should be mandatory for all administrative access attempts. This creates a scenario where attackers can authenticate using only username and password credentials without providing the required second authentication factor.
The operational impact of this vulnerability is significant as it allows malicious actors to gain unauthorized access to container registries and associated resources. Attackers can leverage this bypass to pull, push, or manipulate container images without proper authorization, potentially leading to supply chain compromises, privilege escalation, or data exfiltration. The vulnerability affects organizations that rely on Forgejo for container image management and security enforcement.
This issue aligns with CWE-305 authentication weakness patterns where authentication mechanisms fail to properly enforce required security controls. The vulnerability also maps to ATT&CK technique T1078.004 which covers legitimate credentials obtained through credential access, specifically targeting container registry authentication bypasses. Organizations utilizing Forgejo for docker registry services should immediately implement mitigations including upgrading to version 1.20.5-1 or later, implementing additional authentication layers, and monitoring for unauthorized access attempts.
The root cause lies in the insufficient validation of authentication contexts within the docker login workflow, where the system does not adequately distinguish between different authentication methods and their respective security requirements. This failure demonstrates a critical gap in the application's security model that allows basic authentication flows to bypass mandatory two-factor authentication enforcement mechanisms, creating an attack surface that directly undermines the intended security architecture.
Organizations should implement immediate remediation measures including mandatory version upgrades, configuration reviews of authentication policies, and enhanced monitoring of registry access patterns. Security teams must also consider implementing additional controls such as network segmentation, IP whitelisting, and regular audit logging to detect and prevent exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper authentication flow validation in containerized environments where registry security directly impacts overall infrastructure integrity and compliance requirements.