CVE-2026-2641 in ctags
Summary
by MITRE • 02/18/2026
A weakness has been identified in universal-ctags ctags up to 6.2.1. The affected element is the function parseExpression/parseExprList of the file parsers/v.c of the component V Language Parser. Executing a manipulation can lead to uncontrolled recursion. It is possible to launch the attack on the local host. The exploit has been made available to the public and could be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.
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Analysis
by VulDB Data Team • 02/18/2026
The vulnerability identified in universal-ctags ctags version 6.2.1 represents a critical recursive descent parsing flaw within the V Language Parser component. This weakness exists in the parseExpression and parseExprList functions located in parsers/v.c, where the parser fails to properly validate or limit recursive parsing operations during code analysis. The issue manifests as uncontrolled recursion, which occurs when the parser encounters certain malformed or specially crafted input sequences that trigger infinite recursive calls without proper stack depth limitations or termination conditions. This type of vulnerability falls under CWE-674, which specifically addresses Uncontrolled Recursion, and demonstrates a classic example of how parsing logic can be exploited to consume excessive system resources.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it creates a potential denial of service condition that can severely impact systems relying on ctags for code analysis and indexing operations. When exploited locally, an attacker can craft specific input files that trigger the recursive parsing behavior, causing the ctags process to consume excessive memory and CPU resources until system stability is compromised. The vulnerability is particularly concerning because it affects a widely used code analysis tool that is often integrated into development environments, text editors, and automated build systems, making it a prime target for exploitation in continuous integration pipelines and development workflows. The fact that a public exploit has been made available significantly increases the risk surface and potential for widespread impact.
The attack vector for this vulnerability is particularly dangerous as it requires no network connectivity and can be executed entirely locally on the host system where ctags is installed. This makes it especially problematic in development environments where ctags is frequently invoked during code editing, building, or analysis operations. The vulnerability's exploitation can lead to complete system resource exhaustion, potentially causing system crashes, application hangs, or denial of service conditions that affect legitimate users and automated processes. From an ATT&CK framework perspective, this vulnerability aligns with T1499.004, which covers Resource Exhaustion, and demonstrates how seemingly benign parsing operations can be weaponized to create system-wide availability issues. The lack of response from the project maintainers after early issue reporting creates additional risk, as the vulnerability remains unpatched and continues to pose threats to users who rely on this tool for their development workflows and code analysis tasks.
Mitigation strategies should focus on immediate defensive measures including restricting ctags execution in automated environments, implementing resource limits and timeouts for parsing operations, and disabling V Language Parser functionality if not required for specific use cases. Users should also consider implementing input validation and sanitization for files processed by ctags, particularly in environments where untrusted code may be analyzed. The most effective long-term solution involves applying the official patch when available, but in the interim, system administrators should consider monitoring for unusual resource consumption patterns and implementing process monitoring to detect and terminate runaway ctags processes. Additionally, organizations should consider alternative code analysis tools or implementing sandboxed environments for code analysis operations to prevent local privilege escalation and system compromise scenarios.