CVE-2026-20750 is an improper access control vulnerability (CWE-284) identified in the Gitea Open Source Git Server, a popular self-hosted Git service used for source code management. The vulnerability arises because Gitea does not correctly validate project ownership during organization project operations. Specifically, a user who has write access to projects within one organization can exploit this flaw to modify projects belonging to a different organization. This occurs due to insufficient checks on project ownership boundaries, allowing unauthorized cross-organization project modifications. The vulnerability has a CVSS v3.1 base score of 9.1, reflecting its critical severity. The vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N) indicates that the attack can be performed remotely over the network without any privileges or user interaction, and it impacts confidentiality and integrity severely, though availability is unaffected. The flaw could enable attackers to tamper with source code repositories, potentially injecting malicious code or altering legitimate codebases, which could have downstream effects on software integrity and trust. No patches or known exploits are currently reported, but the vulnerability's nature and severity make it a significant threat to organizations relying on Gitea for code hosting and collaboration.

For European organizations, this vulnerability poses a substantial risk to the confidentiality and integrity of their software development lifecycle. Unauthorized modification of source code repositories can lead to the introduction of backdoors, malware, or other malicious changes that compromise software products and services. This can affect not only the targeted organization but also its customers and partners, especially if the compromised code is distributed widely. The lack of required authentication and user interaction means attackers can exploit this vulnerability remotely, increasing the attack surface. Organizations in sectors with high reliance on software integrity, such as finance, healthcare, and critical infrastructure, face heightened risks. Additionally, the potential for supply chain attacks could undermine trust in European software ecosystems. The vulnerability could disrupt development workflows and necessitate costly incident response and remediation efforts.

Immediate mitigation should focus on restricting project write access strictly to trusted users and organizations until a patch is available. Organizations should audit current access controls and permissions within Gitea instances to ensure no excessive privileges are granted. Network-level controls such as IP whitelisting and VPN access can reduce exposure. Monitoring and logging of project modification activities should be enhanced to detect anomalous changes promptly. Employing multi-factor authentication and integrating Gitea with centralized identity and access management solutions can help enforce stricter access policies. Once a patch or update addressing this vulnerability is released by Gitea, organizations must prioritize its deployment. Additionally, organizations should consider implementing code signing and integrity verification mechanisms to detect unauthorized code changes. Regular security assessments and penetration testing of their Gitea deployments can help identify and remediate similar access control issues proactively.