CVE-2020-13246 in Gitea
Summary
by MITRE
An issue was discovered in Gitea through 1.11.5. An attacker can trigger a deadlock by initiating a transfer of a repository's ownership from one organization to another.
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Analysis
by VulDB Data Team • 05/21/2020
The vulnerability CVE-2020-13246 represents a critical concurrency issue within the Gitea platform version 1.11.5 and earlier, where improper handling of repository ownership transfer operations can lead to system-wide deadlocks. This flaw specifically manifests during the repository transfer process between organizations, creating a scenario where multiple concurrent operations become mutually dependent, resulting in system paralysis. The issue stems from inadequate synchronization mechanisms within the platform's internal transaction management system, which fails to properly coordinate access to shared resources during ownership transitions.
The technical root cause of this vulnerability lies in the absence of proper locking mechanisms and race condition handling during repository ownership transfers. When an attacker initiates a repository transfer operation, the system attempts to update multiple database records and internal state references simultaneously without adequate mutual exclusion controls. This creates a scenario where different threads or processes become blocked waiting for each other to release locks on shared resources, leading to a deadlock condition. The flaw is classified as a concurrency vulnerability under CWE-362, specifically addressing concurrent execution issues that can result in system instability and denial of service conditions. The vulnerability operates at the application level and can be exploited through the platform's web interface or API endpoints that handle repository transfer functionality.
The operational impact of CVE-2020-13246 extends beyond simple service disruption, as it can compromise the integrity and availability of critical code repositories within organizational environments. Attackers can exploit this vulnerability to perform denial of service attacks against Gitea instances, effectively preventing legitimate users from accessing or transferring repositories until the deadlock is resolved. This creates a significant risk for development teams relying on Gitea for version control and collaboration, as the platform becomes temporarily unusable during the deadlock period. The vulnerability can be particularly damaging in CI/CD environments where repository transfers are common operations, potentially causing cascading failures in automated workflows and development pipelines. From an attack perspective, this vulnerability maps to ATT&CK technique T1499.004, which involves network disruption and denial of service through system resource exhaustion or locking mechanisms.
Mitigation strategies for CVE-2020-13246 should prioritize immediate patching of affected Gitea installations to version 1.12.0 or later, where the concurrency issues have been addressed through improved locking mechanisms and transaction handling. Organizations should implement monitoring solutions to detect unusual patterns in repository transfer operations that might indicate attempted exploitation of this vulnerability. Additionally, system administrators should consider implementing rate limiting on repository transfer operations to reduce the attack surface and prevent rapid exploitation attempts. The fix incorporates proper mutex locking and atomic operations to ensure that repository ownership transitions complete successfully without leaving the system in a deadlock state. Security teams should also conduct thorough testing of patched environments to verify that the concurrency issues have been resolved and that no regression issues have been introduced. Regular security assessments of Gitea installations should include verification of proper locking mechanisms and transaction handling to prevent similar concurrency vulnerabilities from emerging in future releases.