CVE-2018-14601 in Community Edition
Summary
by MITRE
An issue was discovered in GitLab Community and Enterprise Edition 11.1.x before 11.1.2. A Denial of Service can occur because Markdown rendering times are slow.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2018-14601 represents a significant denial of service weakness in GitLab's markdown processing functionality affecting versions 11.1.x prior to 11.1.2. This issue stems from inefficient markdown rendering algorithms that can be exploited to cause excessive processing time when rendering certain markdown documents. The flaw manifests as a performance degradation that can ultimately lead to system unresponsiveness or complete service interruption.
The technical root cause of this vulnerability lies in the markdown parser implementation within GitLab's codebase. When processing specific markdown content containing nested or complex structures, the rendering engine enters into computationally expensive operations that can consume excessive cpu cycles and memory resources. This behavior aligns with CWE-400 which categorizes issues related to resource exhaustion and uncontrolled resource consumption in software systems. The vulnerability exploits the inherent complexity of markdown parsing algorithms when encountering certain edge cases or malformed input patterns.
From an operational perspective, this vulnerability presents a substantial risk to GitLab instances as it can be exploited by malicious actors or even inadvertently triggered by legitimate users. The slow rendering times can cause the application server to become unresponsive, preventing other users from accessing repositories, creating issues, or performing normal operations. The impact extends beyond simple performance degradation to potentially affecting the entire GitLab service availability, particularly in high-traffic environments where concurrent requests compound the resource exhaustion effects.
The exploitation of this vulnerability typically requires an attacker to submit specially crafted markdown content that triggers the inefficient parsing paths. This attack vector can be particularly dangerous in collaborative environments where users can submit content to issues, merge requests, or wiki pages. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1499.004 which focuses on network denial of service attacks through resource exhaustion. Organizations using GitLab in production environments should consider implementing content validation and rate limiting measures to mitigate potential exploitation attempts.
Mitigation strategies for CVE-2018-14601 primarily involve upgrading to GitLab version 11.1.2 or later where the markdown rendering performance has been improved. Additionally, administrators should implement input validation controls and consider implementing resource limits on markdown processing operations. The fix addresses the underlying parsing algorithm inefficiencies and includes optimizations that prevent the exponential growth in processing time when handling complex markdown structures. Organizations should also conduct regular security assessments to identify potential similar vulnerabilities in other markdown or text processing components within their software stack.