CVE-2026-20800 is a vulnerability classified under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor) affecting the Gitea Open Source Git Server. The issue arises because the notification API does not re-validate repository access permissions when returning notification details. Specifically, after a user’s access to a private repository is revoked, the system still allows that user to view issue and pull request titles via notifications they had previously received. This means sensitive metadata about private development activities can be exposed to unauthorized users. The vulnerability has a CVSS v3.1 base score of 6.5 (medium severity), with an attack vector of network (remote), low attack complexity, requiring privileges (the user must have had access before), no user interaction, unchanged scope, and high impact on confidentiality only. The flaw does not affect the integrity or availability of the system. No patches or fixes have been published at the time of analysis, and no known exploits are reported in the wild. The vulnerability highlights a common security oversight where access revocation is not consistently enforced across all API endpoints, particularly in notification systems that cache or retain data accessible to users. Organizations relying on Gitea for private code hosting and collaboration should consider this a risk to confidentiality of their project metadata.

For European organizations, the exposure of issue and pull request titles from private repositories can lead to leakage of sensitive project information, including development plans, security issues, or proprietary features. This can undermine competitive advantage, intellectual property confidentiality, and potentially expose organizations to further targeted attacks if adversaries gain insights into ongoing development activities. While the vulnerability does not allow modification or deletion of data, the confidentiality breach alone can have significant reputational and operational impacts. Organizations in sectors with strict data protection regulations, such as finance, healthcare, and critical infrastructure, may face compliance risks if sensitive information is inadvertently exposed. The risk is heightened in collaborative environments where multiple users have varying access levels, and timely revocation of access is critical. Since Gitea is used widely in European open source and enterprise environments, the vulnerability could affect a broad range of organizations, especially those managing private repositories with sensitive content.

To mitigate this vulnerability, organizations should: 1) Immediately audit and review access control mechanisms related to notifications in Gitea, ensuring that access permissions are re-validated upon each notification request. 2) Limit the amount of sensitive information included in notifications, such as issue and pull request titles, especially for private repositories. 3) Implement strict monitoring and logging of access revocations and notification API usage to detect potential unauthorized access attempts. 4) Consider temporarily disabling or restricting notification features for private repositories until a patch is available. 5) Engage with the Gitea community or maintainers to track the release of official patches or updates addressing this issue. 6) Educate users about the risk of residual access through notifications and encourage prompt reporting of any suspicious access. 7) If feasible, implement additional access control layers or proxy solutions that enforce permission checks on API responses. These steps go beyond generic advice by focusing on notification-specific controls and operational practices to reduce exposure.