Description

Personal access token scope enforcement bypass on the repository home page (`GET /{owner}/{repo}`) discloses private repository contents

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "4.3",
  "pubDate": "2026-08-13T17:17:28.437Z",
  "pubdate": "2026-08-13T17:17:28.437Z",
  "executiveSummary": "A vulnerability exists involving personal access token scope enforcement bypass on the repository home page (GET /{owner}/{repo}), which leads to the unauthorized disclosure of private repository contents. This security flaw allows unauthorized entities to circumvent established authorization boundaries associated with specific token scopes, exposing sensitive code and repository metadata to principals that should otherwise lack access.\nThe vulnerability directly impacts repository confidentiality by leaking private repository information through standard HTTP GET requests targeting the repository landing page. Attackers with restricted personal access tokens or improperly scoped credentials can leverage this flaw to harvest unauthorized data, increasing the risk of intellectual property theft, credential leakage, and further compromise of internal development ecosystems. The risk implications are severe for organizations relying on granular token permissions to enforce the principle of least privilege across their source code management infrastructure.\nExploitation of this vulnerability requires an adversary to interact with the affected system using a personal access token that lacks the requisite permissions or scopes for the targeted private repository. The attack vector is exposed via network requests, specifically targeting the repository home page route, requiring no complex interaction or prior execution privileges beyond possessing an applicable authentication token.",
  "technicalDetails": "The root cause of this vulnerability lies in the improper authorization validation logic executed during the handling of GET /{owner}/{reporequests on the repository home page component. Specifically, the application fails to adequately verify whether the provided personal access token possesses the exact required repository scopes before rendering or returning private repository content within the HTTP response.\nThe vulnerable component is the access control and routing middleware responsible for processing repository home page requests and enforcing token scope boundaries. Under normal operating conditions, the system should intercept requests lacking sufficient scope validation and return an authorization error, such as a 403 Forbidden or 404 Not Found status. However, due to the bypass flaw, the request processing pipeline improperly permits the retrieval and rendering of private repository contents.\nThe exploitation method involves an attacker issuing a crafted HTTP GET request to the endpoint GET /{owner}/{repousing a personal access token with insufficient or restricted scopes. When the server processes this request, the authorization check fails to enforce scope constraints, resulting in the backend retrieving and returning private repository details, metadata, and potentially source code contents directly in the response payload. The attack flow operates entirely over the network layer, requiring standard HTTP communication capabilities and a valid personal access token as an authentication requirement.\nThe vulnerability requires network exposure of the repository home page endpoint and authentication via a personal access token, albeit one with improperly validated scopes. No elevated administrative privileges are required by the attacker beyond standard platform authentication, lowering the barrier to successful exploitation. Post-exploitation impact includes the unauthorized exfiltration of proprietary source code, internal documentation, configuration files, and other sensitive assets hosted within private repositories, severely undermining confidentiality guarantees provided by token scope configurations."
}