CVE-2026-20888 in Gitea
Summary
by MITRE • 01/23/2026
Gitea does not properly verify authorization when canceling scheduled auto-merges via the web interface. A user with read access to pull requests may be able to cancel auto-merges scheduled by other users.
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Analysis
by VulDB Data Team • 01/24/2026
The vulnerability identified as CVE-2026-20888 represents a critical authorization flaw within the Gitea platform that undermines the security model governing pull request management operations. This issue specifically affects the web interface functionality for canceling scheduled auto-merges, creating a privilege escalation scenario where users with minimal read access can manipulate critical merge operations. The flaw stems from insufficient validation of user permissions during the auto-merge cancellation process, allowing unauthorized individuals to interfere with automated workflows that should only be accessible to users with appropriate write or administrative privileges.
The technical implementation of this vulnerability resides in the authorization checking mechanisms within Gitea's web interface components responsible for handling auto-merge cancellation requests. When a user attempts to cancel a scheduled auto-merge, the system fails to properly verify whether the requesting user possesses the necessary permissions to perform this action. This validation gap occurs at the application layer where access control checks are either absent or improperly implemented, allowing a user with read-only access to pull requests to submit cancellation requests that are processed without adequate authorization verification. The flaw operates through the standard web interface pathways and does not require special tools or techniques beyond normal user access to the platform.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables potential disruption of continuous integration and deployment workflows that rely on automated merge operations. An attacker with read access could systematically cancel auto-merges scheduled by other team members, causing delays in software releases, interfering with automated testing processes, and potentially creating conflicts in version control systems. This vulnerability particularly affects collaborative development environments where multiple team members contribute to the same repositories, as it allows any user with read access to disrupt the automated workflows of their colleagues. The consequences could include operational delays, increased manual intervention requirements, and potential security implications if auto-merges are canceled during critical security updates.
Organizations utilizing Gitea for their source code management and collaboration needs face significant risks from this authorization flaw, particularly in environments where access control is critical for maintaining software development integrity. The vulnerability creates an attack surface that could be exploited by both malicious insiders and external attackers who gain read access to repositories. Security teams should prioritize this issue as it represents a direct violation of the principle of least privilege, where users can perform actions beyond their intended access levels. This flaw aligns with CWE-285, which addresses improper authorization in software systems, and could potentially map to ATT&CK technique T1078.004 related to valid accounts for lateral movement and privilege escalation.
Mitigation strategies for CVE-2026-20888 should focus on implementing robust authorization checks within the web interface components responsible for auto-merge cancellation functionality. Organizations should immediately update to patched versions of Gitea where the authorization verification has been strengthened to ensure that only users with appropriate write permissions can cancel scheduled auto-merges. Additionally, security teams should implement monitoring for unauthorized cancellation attempts and review access control policies to ensure that read-only users cannot perform operations that should be restricted to authorized maintainers. The implementation of proper access control lists and role-based permissions should be enforced for all merge-related operations to prevent similar vulnerabilities from occurring in other parts of the application. Organizations should also consider implementing additional logging and audit trails for auto-merge operations to detect and respond to unauthorized activities more effectively.