CVE-2025-27423: Vim Text Editor RCE Vulnerability

CVE-2025-27423 Overview

CVE-2025-27423 is a command injection vulnerability affecting Vim, the widely-used open source command line text editor. The vulnerability exists in the tar.vim plugin, which provides functionality for viewing and editing tar archive files directly within Vim. Due to improper input sanitization when processing tar archive filenames, an attacker can craft a malicious tar archive that executes arbitrary shell commands when opened.

Critical Impact

Attackers can achieve arbitrary shell command execution by tricking users into opening specially crafted tar archives in Vim, potentially leading to complete system compromise with the privileges of the user running Vim.

Affected Products

• Vim versions 9.1.0858 through 9.1.1163
• NetApp HCI Compute Node (firmware dependent)
• Any system with vulnerable Vim versions and the tar.vim plugin enabled

Discovery Timeline

• 2025-03-03 - CVE-2025-27423 published to NVD
• 2025-08-18 - Last updated in NVD database

Technical Details for CVE-2025-27423

Vulnerability Analysis

This vulnerability is classified as CWE-77 (Command Injection), a serious weakness where attacker-controlled input is incorporated into commands executed by the system shell. The tar.vim plugin processes tar archives to display and edit their contents within Vim. Starting with version 9.1.0858, the plugin uses the :read ex command to append file contents below the cursor position. However, filenames extracted from tar archives are not properly sanitized before being passed to this command.

The attack requires local access to the vulnerable system and user interaction—specifically, the victim must open a malicious tar archive using Vim. Successful exploitation can result in high impact to both confidentiality and integrity, as arbitrary commands execute with the privileges of the Vim user. The behavior is also dependent on the shell configured in Vim's 'shell' option, which defaults to the user's $SHELL environment variable.

Root Cause

The root cause lies in insufficient input validation within the tar.vim plugin. When the plugin extracts filename information from tar archives, it directly incorporates these values into Vim's :read command without proper escaping or sanitization. Tar archives can contain filenames with arbitrary characters, including shell metacharacters and command sequences. When these unsanitized filenames are passed to the shell for processing, embedded commands are executed.

Attack Vector

The attack vector is local with required user interaction. An attacker must craft a malicious tar archive containing specially formatted filenames that include shell command sequences. When a user opens this tar archive in Vim with the tar.vim plugin active, the malicious filename is processed, and the embedded shell commands execute. The attacker could distribute the malicious archive through email attachments, shared file systems, downloaded archives, or any other file delivery mechanism.

The exploitation depends on the shell being used by Vim. Different shells have varying metacharacter interpretations, which may affect whether specific payloads execute successfully. Common shells like bash, zsh, and sh are typically vulnerable to command injection through this vector.

Detection Methods for CVE-2025-27423

Indicators of Compromise

• Unusual shell processes spawned as child processes of Vim instances
• Vim processes accessing unexpected network resources or system files
• Tar archives with suspicious or malformed filenames containing shell metacharacters such as backticks, semicolons, or $() sequences
• Log entries showing Vim executing commands unrelated to normal text editing operations

Detection Strategies

• Monitor process trees for Vim spawning unexpected child shell processes
• Implement file integrity monitoring on systems where Vim is commonly used
• Deploy endpoint detection rules that alert on command injection patterns in process arguments
• Analyze tar archives before extraction for filenames containing shell metacharacters or command sequences

Monitoring Recommendations

• Enable audit logging for shell command execution on critical systems
• Configure SentinelOne to detect anomalous process behavior from text editors
• Implement file inspection policies for incoming tar archives in email gateways and file shares
• Review Vim configuration files for unexpected modifications to the 'shell' option

How to Mitigate CVE-2025-27423

Immediate Actions Required

• Update Vim to version 9.1.1164 or later immediately
• Disable the tar.vim plugin if updates cannot be applied immediately by adding let g:loaded_tar = 1 to your vimrc
• Avoid opening untrusted tar archives in Vim until the patch is applied
• Review recently opened tar archives from untrusted sources for signs of exploitation

Patch Information

The Vim development team has addressed this vulnerability in patch v9.1.1164. The fix ensures proper sanitization of filenames extracted from tar archives before they are passed to shell commands. Two commits address this issue and can be reviewed on the Vim GitHub repository. Additional details are available in the GitHub Security Advisory GHSA-wfmf-8626-q3r3. NetApp users should consult the NetApp Security Advisory for affected product guidance.

Workarounds

• Disable the tar.vim plugin by setting let g:loaded_tar = 1 in your ~/.vimrc or Vim configuration
• Use alternative tools such as tar -tvf or graphical archive managers to inspect tar files before opening in Vim
• Configure restrictive shell settings for Vim by setting set shell=/bin/sh with a minimal shell
• Implement application whitelisting to prevent Vim from spawning unexpected shell commands

# Disable tar.vim plugin in Vim configuration
echo 'let g:loaded_tar = 1' >> ~/.vimrc
echo 'let g:loaded_tarPlugin = 1' >> ~/.vimrc

# Verify Vim version after patching
vim --version | head -1