CVE-2022-48339 in Emacs
Summary
by MITRE • 02/21/2023
An issue was discovered in GNU Emacs through 28.2. htmlfontify.el has a command injection vulnerability. In the hfy-istext-command function, the parameter file and parameter srcdir come from external input, and parameters are not escaped. If a file name or directory name contains shell metacharacters, code may be executed.
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Analysis
by VulDB Data Team • 07/26/2025
The vulnerability identified as CVE-2022-48339 represents a critical command injection flaw within GNU Emacs version 28.2 and earlier, specifically within the htmlfontify.el module. This issue arises from inadequate input validation and sanitization practices in the hfy-istext-command function, where external parameters file and srcdir are directly incorporated into shell commands without proper escaping or sanitization. The flaw demonstrates a classic command injection vulnerability that allows attackers to execute arbitrary code on systems running vulnerable versions of Emacs.
The technical implementation of this vulnerability stems from the improper handling of user-supplied data within the htmlfontify.el module, which is designed to convert text files into HTML format. When the hfy-istext-command function processes file names or directory paths containing shell metacharacters such as semicolons, ampersands, or backticks, these characters are interpreted by the underlying shell as command delimiters or operators. This creates an exploitation vector where malicious input can be transformed into executable shell commands, effectively bypassing normal input validation mechanisms and granting unauthorized code execution capabilities.
From an operational perspective, this vulnerability poses significant risks to users who employ GNU Emacs for processing untrusted content or when the application is used in automated environments. The impact extends beyond simple code execution to potentially compromise entire systems, as attackers could leverage this vulnerability to gain persistent access, escalate privileges, or deploy additional malware. The vulnerability affects all versions of GNU Emacs up to and including 28.2, making it a widespread concern for organizations relying on this popular text editor.
The security implications align with CWE-78, which specifically addresses "Improper Neutralization of Special Elements used in OS Command" and corresponds to techniques documented in the MITRE ATT&CK framework under T1059.001 for Command and Scripting Interpreter. Organizations should prioritize immediate patching of affected systems, as the vulnerability can be exploited remotely through web-based interfaces or local file processing scenarios. Additionally, implementing strict input validation policies and ensuring proper shell command escaping mechanisms are critical mitigation strategies that should be enforced across all affected deployments.
Mitigation efforts should include upgrading to GNU Emacs version 28.3 or later, where the vulnerability has been addressed through proper input sanitization. System administrators should also consider implementing network segmentation and access controls to limit exposure, while monitoring for suspicious file processing activities that might indicate exploitation attempts. The vulnerability underscores the importance of secure coding practices, particularly when handling external inputs in shell command contexts, and serves as a reminder of the critical need for thorough input validation and sanitization in all software components that interact with operating system commands.