Vim for Windows Flaw Lets Attackers Execute Arbitrary Code

A high security vulnerability has been discovered in Vim for Windows that could allow attackers to run malicious code on affected systems.

The flaw, tracked as CVE-2025-66476, affects Vim versions earlier than 9.1.1947 and received a high severity rating due to its serious implications for Windows users.

The vulnerability stems from an uncontrolled search path issue on Windows systems. When Vim performs tasks that require external commands, it searches for executable files in the current working directory before checking system paths.

This search order creates a dangerous opening for attackers who can plant malicious executables in directories where users are working.

How the Attack Works

The attack scenario is straightforward and concerning. Imagine a user cloning a malicious repository from the internet and opening one of its files in Vim.

The repository creator could have included a trojanized executable with a common name like findstr.exe.

When the user runs a grep command in Vim, the text editor searches for findstr.exe and finds the malicious version in the current directory rather than the legitimate system binary in WindowsSystem32.

This causes Vim to execute the attacker’s code with the same privileges as the user running Vim.

This vulnerability can be triggered by several Vim features that invoke external utilities, including the :grep command, external command execution via :!, filter commands,: make for build tool integrations, and any feature that uses the system() function in Vim scripts.

A user doesn’t need special administrative privileges to become a victim, and the attack can occur simply by opening a file in a compromised directory.

The Vim project rated this vulnerability as high severity because arbitrary code execution is possible without requiring elevated permissions.

An attacker could install malware, steal sensitive data, modify files, or perform other malicious actions using the compromised user’s account privileges.

The fact that no special permissions are needed and the vulnerability can be triggered through normal Vim operations makes this threat particularly dangerous.

The Vim development team has addressed the issue in version 9.1.1947. Users running Vim on Windows should upgrade immediately to this patched version or later to eliminate the vulnerability.

The vulnerability was initially reported by Simon Zuckerbraun of Trend Micro’s Zero Day Initiative, who demonstrated the issue by showing how Vim could be tricked into launching the Windows Calculator instead of legitimate system utilities.

This vulnerability highlights the importance of careful path handling in applications, especially on Windows where the current directory has traditionally held a privileged position in the search path.

Users should be cautious about opening files from untrusted sources, and Windows Vim users should prioritize this security update to protect their systems from potential exploitation.

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