CVE-2023-49948 in Forgejo
Summary
by MITRE • 12/03/2023
Forgejo before 1.20.5-1 allows remote attackers to test for the existence of private user accounts by appending .rss (or another extension) to a URL.
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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 significant information disclosure flaw that allows remote attackers to enumerate private user accounts through simple URL manipulation techniques. The vulnerability stems from improper access control implementation within the application's feed handling mechanism, where the system fails to properly validate user permissions before serving content through rss or similar feed extensions. Attackers can exploit this by simply appending .rss or other feed extensions to user profile URLs, potentially discovering the existence of private accounts without authentication. This type of vulnerability falls under the category of insecure direct object reference as outlined in CWE-639, where the application provides direct access to objects based on user-supplied input without proper authorization checks. The flaw enables attackers to perform reconnaissance activities and gather intelligence about the user base, which could serve as a precursor to more sophisticated attacks targeting specific accounts.
The technical implementation of this vulnerability occurs at the application layer where the feed endpoint logic does not adequately verify whether the requesting user has proper authorization to access the target resource. When a URL with a feed extension is accessed, the system should validate the session credentials and permissions before returning any content, but this validation is missing or incomplete in affected versions. The attack vector is particularly concerning because it requires minimal technical expertise to execute and can be automated at scale to discover multiple private accounts within a system. This vulnerability directly maps to techniques described in the attack pattern taxonomy under ATT&CK tactic TA0007 (Discovery) and specifically relates to T1087.001 (Account Discovery) and T1592.004 (Resource Hijacking). The flaw demonstrates a fundamental breakdown in the principle of least privilege, where the system exposes private information through unintended access paths that should be restricted to authorized users only.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to build comprehensive profiles of users within the Forgejo instance and potentially identify high-value targets for further exploitation. Organizations using affected versions of Forgejo face risks including targeted social engineering attacks, credential stuffing attempts against discovered accounts, and potential privilege escalation if the enumeration reveals administrative users. The vulnerability also impacts the overall security posture by reducing the effectiveness of access control mechanisms and potentially exposing sensitive user data that should remain private. This type of reconnaissance capability can be particularly damaging in environments where user privacy is paramount, such as enterprise collaboration platforms, open source project hosting services, or any system where user confidentiality is a primary concern. The flaw creates a persistent threat vector that remains active as long as the vulnerable version is deployed, making it critical for organizations to assess their exposure and implement appropriate mitigations.
Organizations should immediately upgrade to Forgejo version 1.20.5-1 or later to address this vulnerability, as the fix involves implementing proper access control validation for feed endpoints. Additional mitigations include implementing rate limiting on feed requests to prevent automated enumeration, configuring proper authentication checks before serving any feed content, and conducting regular security assessments to identify similar access control flaws. Security teams should also implement monitoring for unusual feed request patterns that could indicate enumeration attempts, and establish incident response procedures for detecting and responding to unauthorized account discovery activities. The vulnerability highlights the importance of comprehensive access control testing and validation of all application endpoints, particularly those that serve content or provide data access through non-standard interfaces. Organizations should also consider implementing network-level controls to restrict access to feed endpoints and ensure that only authenticated users with appropriate permissions can access sensitive data through these mechanisms.