CVE-2026-112887 in Gitea
Summary
by MITRE • 11/01/2026
Gitea Actions task tokens authenticate to the REST API as a shared system user with a negative ID, which repository, organization, project and key filters treated as having no owner restriction, and the token carried no API scope to restrict user-scoped routes. A user who can run a workflow could use the job's token with `GET /api/v1/user/repos` to list every repository on the instance, including private repositories of other users and organizations, with their metadata. Repository contents remained protected by per-repository permission checks. System users now own nothing, and `/api/v1/user` routes other than `GET /api/v1/user` accept only individual and bot accounts.
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Analysis
by VulDB Data Team • 11/01/2026
The vulnerability in Gitea Actions stems from a fundamental flaw in how task tokens are authenticated and authorized when interacting with the REST API. When an action workflow is executed, it receives a token that authenticates to the backend as a shared system user characterized by a negative identifier. This architectural design choice inadvertently bypasses standard ownership checks because repository, organization, project, and key filters associated with this specific system identity are treated as having no owner restriction. Consequently, API endpoints that rely on these filters do not enforce the expected isolation boundaries between different users or organizations within the instance.
This lack of proper access control allows any user who has the ability to execute a workflow in their repository to leverage the job's token to enumerate resources across the entire Gitea instance. Specifically, by issuing requests to endpoints such as GET /api/v1/user/repos, an attacker can retrieve a comprehensive list of all repositories hosted on the server. This enumeration includes private repositories belonging to other users and organizations, exposing sensitive metadata associated with these projects. The exposure of this information constitutes a significant breach of confidentiality regarding project visibility and organizational structure, even though the actual contents of the repositories remain protected by per-repository permission checks that prevent direct file access or modification without proper credentials.
From an industry standard perspective, this vulnerability aligns closely with CWE-284 Improper Access Control, as the application fails to restrict unauthorized users from accessing resources they should not be able to view. Furthermore, it maps to MITRE ATT&CK technique T1087 Account Discovery, where adversaries enumerate accounts or other user-related information within a system to build an attack plan. The ability to list private repositories effectively provides attackers with valuable intelligence about the target environment, potentially facilitating further reconnaissance and targeted attacks against specific projects that may have weaker security postures than others on the platform.
The operational impact of this flaw is primarily informational disclosure rather than direct data exfiltration or system compromise. While an attacker cannot read the code within private repositories due to persistent file-level permissions, they can gain a complete map of the organization's assets, including project names, descriptions, and visibility settings. This information can be used for social engineering attacks, targeted phishing campaigns against specific teams, or identifying high-value targets for future exploitation attempts where other vulnerabilities might exist. The exposure undermines trust in the platform's isolation guarantees and could lead to reputational damage if sensitive project metadata is leaked publicly through third-party integrations that consume these API responses.
To mitigate this vulnerability, Gitea has implemented a structural change wherein system users no longer own any resources, effectively removing the ambiguity around ownership filters for shared identities. Additionally, routes under /api/v1/user have been hardened to accept only individual and bot accounts, excluding the problematic shared system user from accessing these endpoints except for specific read-only operations like GET /api/v1/user which do not expose broad enumeration capabilities. Administrators should ensure their instances are updated to versions that include this fix. In the interim, if an update is not immediately possible, restricting API access through network-level controls or implementing strict rate limiting and monitoring on user-facing endpoints can help detect abnormal enumeration patterns indicative of exploitation attempts. Regular audits of workflow permissions and minimizing the scope of tokens issued to actions can also reduce the attack surface associated with this class of issues.