CVE-2026-15975 in GitLab
Summary
by MITRE • 07/29/2026
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 11.8 before 19.0.5, 19.1 before 19.1.3, and 19.2 before 19.2.1 that under certain conditions could have allowed an unauthenticated user to cause a denial of service due to insufficient resource throttling when processing merge request discussions.
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Analysis
by VulDB Data Team • 07/29/2026
This vulnerability represents a denial of service weakness in GitLab's merge request discussion processing functionality that could be exploited by unauthenticated attackers. The flaw stems from inadequate resource throttling mechanisms within the application's handling of merge request discussions, allowing malicious actors to consume excessive system resources without proper authentication requirements. The vulnerability affects multiple version ranges including 11.8 through 19.0.4, 19.1 through 19.1.2, and 19.2 through 19.2.0, indicating a widespread impact across several major release lines. The technical implementation appears to lack proper rate limiting or resource consumption controls when processing discussion-related requests, enabling attackers to submit multiple concurrent requests that exhaust available system resources.
The operational impact of this vulnerability extends beyond simple service disruption as it creates a vector for resource exhaustion attacks that can potentially affect the entire GitLab instance. Attackers could leverage this weakness to consume CPU cycles, memory, and other system resources through carefully crafted merge request discussion requests, leading to degraded performance or complete unavailability of the platform. The fact that no authentication is required to exploit this vulnerability makes it particularly dangerous as it allows anyone on the internet to potentially disrupt services without needing valid credentials. This type of vulnerability aligns with CWE-400 which specifically addresses resource exhaustion issues and represents a classic example of insufficient resource management in web applications.
From an attack perspective, this vulnerability fits within the broader category of denial of service attacks and could be categorized under ATT&CK technique T1499 which covers network denial of service. The exploitation pattern suggests that attackers would likely submit numerous merge request discussion requests or manipulate existing discussions to trigger resource exhaustion conditions. The remediation implemented by GitLab involved adding proper throttling mechanisms to limit the rate at which merge request discussion processing can occur, preventing any single user or set of requests from consuming disproportionate resources. Organizations should consider implementing additional monitoring for unusual patterns in merge request activity and resource consumption as early detection mechanisms.
The vulnerability demonstrates how seemingly minor functionality within complex applications can create significant security risks when proper resource management controls are not implemented. The fix addresses the root cause by introducing rate limiting that prevents abuse of the merge request discussion processing system, ensuring that legitimate users can continue to utilize the platform without disruption. This type of remediation approach aligns with industry best practices for preventing resource exhaustion attacks and reflects the importance of implementing proper access controls and resource management in collaborative development platforms. Organizations should verify that their GitLab installations have been updated to the patched versions and consider reviewing other similar functionality within their systems for potential resource throttling requirements.