Severity
High
Analysis Summary
A critical vulnerability has been discovered in Vim for Windows, identified as CVE-2025-66476, which allows attackers to execute arbitrary code on users’ systems. This flaw affects all Vim versions prior to 9.1.1947 and has been rated high severity with a CVSS score of high. The vulnerability arises from the way Vim searches for external programs on Windows: it looks in the current working directory first before checking system directories. This search order creates an opportunity for attackers to inject malicious executables into directories that users commonly work in.
The vulnerability specifically targets commands in Vim that rely on external programs, such as grep or make. Attackers can place a malicious file named to mimic a legitimate system executable, like findstr.exe into a project folder. When a user opens a file from that folder and runs a command in Vim, the malicious file is executed instead of the legitimate system program. This allows arbitrary code execution with the same privileges as the user running Vim, making the flaw particularly dangerous in development environments or when handling files from untrusted sources.
The attack does not require elevated permissions, and any user with write access to a directory can potentially exploit it. Scenarios such as cloning a malicious repository or opening untrusted files could trigger the attack during routine development tasks, including searching through code or running build tools. The vulnerability is relevant to both Vim and gVim users on Windows, highlighting the risk posed by uncontrolled search paths in development software.
Vim has addressed the vulnerability in version 9.1.1947, which changes the executable search behavior to prevent prioritizing files in the current working directory. Users are strongly advised to update immediately to this patched version or later. This incident underscores the importance of keeping development tools up to date and exercising caution when opening files from unknown or untrusted sources to prevent potential code-execution attacks.
Impact
- Gain Access
- Code Execution
Indicators of Compromise
CVE
- CVE-2025-66476
Affected Vendors
Remediation
- Update Vim immediately to version 9.1.1947 or later, which fixes the vulnerability.
- Avoid opening files from untrusted sources or unknown directories in Vim until patched.
- Check project directories for suspicious or unexpected executables that could mimic system commands.
- Restrict user write permissions on critical directories to reduce the risk of attackers planting malicious files.
- Use alternative tools cautiously for commands like grep or make if working in untrusted environments.
- Educate developers and users about the risks of uncontrolled search paths and malicious repositories.
- Regularly review and audit software for updates and known vulnerabilities.