CVE-2026-93960 in Pixelfed
Summary
by MITRE • 09/20/2026
A vulnerability was identified in Pixelfed up to 0.12.11. Impacted is the function instancePeers of the file app/Http/Controllers/Api/ApiV1Controller.php of the component OAuth Scope Handler. Such manipulation of the argument ID leads to missing authentication. The attack may be performed from remote. The exploit is publicly available and might be used. Upgrading to version 0.12.10 is recommended to address this issue. The name of the patch is 68dca5097305fa0065d029587b2233524636025a. Upgrading the affected component is advised.
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Analysis
by VulDB Data Team • 09/21/2026
The vulnerability identified in Pixelfed versions up to 0.12.11 represents a critical authentication bypass within the OAuth Scope Handler component, specifically affecting the instancePeers function located in app/Http/Controllers/Api/ApiV1Controller.php. This flaw stems from improper validation of the ID argument passed to this endpoint, allowing an attacker to manipulate input parameters to circumvent standard access control mechanisms. The root cause is classified under CWE-287, which denotes Improper Authentication, as the application fails to correctly verify the identity or authorization level of the user attempting to access protected resources through this specific API route.
From a technical perspective, the manipulation of the ID argument allows an attacker to bypass the intended authentication checks that should restrict access based on OAuth scopes and user permissions. By crafting a request with a specifically altered or malformed ID parameter, the application incorrectly grants access without requiring valid credentials or proper scope validation. This type of vulnerability is particularly dangerous because it undermines the fundamental security model of the API, which relies on strict adherence to authentication protocols to ensure that only authorized users can perform specific actions such as viewing peer lists or interacting with other instances in a Fediverse context.
The operational impact of this vulnerability is severe due to its remote exploitability and the availability of public proof-of-concept code. An attacker located remotely can leverage this flaw to gain unauthorized access to sensitive data or functionality that should be restricted to authenticated users. This could lead to information disclosure, where private user data or instance-specific configurations are exposed, as well as potential privilege escalation if the affected endpoint controls administrative functions. The existence of public exploits significantly lowers the barrier for entry, enabling less sophisticated attackers to compromise the integrity and confidentiality of Pixelfed instances running vulnerable versions.
This vulnerability aligns with MITRE ATT&CK technique T1078, Valid Accounts, specifically in the context of using valid credentials or bypassing authentication mechanisms to gain initial access. It also relates to CWE-209, which involves the generation of an error message that includes sensitive information, although the primary issue here is the lack of authentication rather than informational leakage via errors. The flaw highlights a common pitfall in API development where input validation and authorization checks are not consistently applied across all endpoints, particularly those handling complex relationships like peer-to-peer interactions in distributed social networks.
To mitigate this risk, it is strongly recommended to upgrade Pixelfed immediately to version 0.12.10 or later, which includes the patch identified by commit hash 68dca5097305fa0065d029587b2233524636025a. This update addresses the underlying logic error in the instancePeers function that allowed for authentication bypass. Organizations operating Pixelfed instances should verify their current version and apply this upgrade as a priority to restore proper access controls. Additionally, implementing Web Application Firewall rules can provide temporary protection by blocking requests with suspiciously manipulated ID parameters until the software update is fully deployed across all affected infrastructure components.