CVE-2022-4515 in Exuberant Ctags
Summary
by MITRE • 12/20/2022
A flaw was found in Exuberant Ctags in the way it handles the "-o" option. This option specifies the tag filename. A crafted tag filename specified in the command line or in the configuration file results in arbitrary command execution because the externalSortTags() in sort.c calls the system(3) function in an unsafe way.
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Analysis
by VulDB Data Team • 01/04/2026
The vulnerability identified as CVE-2022-4515 resides within Exuberant Ctags, a widely used tool for generating tag files for source code navigation. This flaw manifests in the improper handling of the "-o" command line option which determines the output tag filename. The vulnerability represents a critical security issue that can be exploited to achieve arbitrary code execution on systems running affected versions of the tool. The flaw specifically impacts how the tool processes user-supplied filenames through its externalSortTags() function in sort.c, creating a dangerous condition where malicious input can be interpreted as executable commands.
The technical implementation of this vulnerability stems from the unsafe usage of the system(3) function within the externalSortTags() routine. When a crafted tag filename is provided through command line arguments or configuration files, the system call executes with insufficient input validation, allowing attackers to inject malicious commands that get processed by the underlying shell. This represents a classic command injection vulnerability that leverages the tool's legitimate functionality to execute unintended operations. The vulnerability directly maps to CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-94, covering inadequate control of generation of code, since the tool essentially generates and executes code based on user input without proper sanitization.
The operational impact of this vulnerability extends beyond simple code execution, as it can be exploited in various attack scenarios. An attacker could leverage this flaw in automated build systems, continuous integration pipelines, or development environments where Exuberant Ctags is invoked with untrusted input. The vulnerability affects systems where the tool is used in contexts such as source code analysis, documentation generation, or automated testing frameworks. In enterprise environments, this could enable privilege escalation or lateral movement if the tool is executed with elevated permissions, as the arbitrary execution could potentially be used to establish persistent access or escalate privileges within the system.
Mitigation strategies for CVE-2022-4515 should focus on immediate patching of affected Exuberant Ctags installations, as this represents the most effective defense against exploitation. Organizations should also implement input validation measures to prevent untrusted filenames from being passed to the tool, particularly in automated environments where the tool might receive input from multiple sources. Network segmentation and privilege separation can help limit the potential damage if exploitation occurs, while monitoring systems should be configured to detect unusual execution patterns or command invocations related to tag file generation. The ATT&CK framework categorizes this vulnerability under T1059.001 for Command and Scripting Interpreter and T1203 for Exploitation for Client Execution, highlighting the need for comprehensive defensive measures that address both the execution of malicious commands and the exploitation of the tool's legitimate functionality. Additionally, security teams should consider implementing runtime protections and application whitelisting to prevent unauthorized execution of the vulnerable tool in critical environments.