CVE-2021-22216 in Community Edition
Summary
by MITRE • 06/09/2021
A denial of service vulnerability in all versions of GitLab CE/EE before 13.12.2, 13.11.5 or 13.10.5 allows an attacker to cause uncontrolled resource consumption with a very long issue or merge request description
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Analysis
by VulDB Data Team • 06/11/2021
The CVE-2021-22216 vulnerability represents a critical denial of service flaw affecting GitLab Community and Enterprise editions across multiple version streams. This vulnerability stems from inadequate input validation mechanisms within the GitLab platform's handling of issue and merge request descriptions. Attackers can exploit this weakness by crafting exceptionally long descriptive text that triggers uncontrolled resource consumption within the GitLab application servers. The vulnerability specifically targets the parsing and processing logic responsible for managing user-generated content in issue tracking and code review workflows. The flaw allows malicious actors to consume excessive computational resources through carefully constructed payload sequences that overwhelm the system's memory and processing capabilities.
The technical implementation of this vulnerability leverages the inherent design of GitLab's content processing pipeline where user input is not properly sanitized or limited in length before being processed. When a user submits an issue or merge request with an extraordinarily long description, the GitLab backend attempts to parse, validate, and store this content without appropriate bounds checking. This lack of input limitation creates a condition where resource allocation becomes proportional to the input size, leading to memory exhaustion and system instability. The vulnerability operates at the application layer and can be triggered through standard user interface interactions or API calls, making it particularly dangerous as it requires no privileged access or special authentication. The resource consumption manifests as excessive memory usage and cpu processing time, ultimately leading to service disruption and system unresponsiveness.
The operational impact of CVE-2021-22216 extends beyond simple service interruption to encompass broader security implications for organizations relying on GitLab for their development workflows. System administrators may experience complete service outages, particularly in environments with limited computational resources where the vulnerability can quickly exhaust available memory pools. This vulnerability directly affects the availability aspect of the CIA triad and can be classified under CWE-770, which addresses allocation of resources without limits or throws. The attack vector allows for significant system degradation without requiring advanced technical skills, making it a particularly dangerous threat to organizations of all sizes. Additionally, the vulnerability can be exploited as part of larger attack campaigns where attackers use resource exhaustion techniques to create conditions for further exploitation or to disrupt business operations.
Mitigation strategies for CVE-2021-22216 primarily focus on implementing immediate version upgrades to patched GitLab releases including 13.12.2, 13.11.5, or 13.10.5, depending on the organization's current version. Organizations should also implement application-level rate limiting and input length restrictions for issue and merge request descriptions as temporary compensating controls. Network-level monitoring should be enhanced to detect unusual resource consumption patterns that may indicate exploitation attempts. Security teams should consider implementing automated alerting systems that trigger when resource usage exceeds normal thresholds, particularly during peak usage periods. The vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and can be addressed through defensive measures such as implementing proper input validation and resource management policies. Organizations should also review their incident response procedures to ensure rapid identification and containment of potential exploitation attempts, as the vulnerability can be leveraged to disrupt critical development and collaboration workflows.