CVE-2023-2610: Vim Integer Overflow Vulnerability

CVE-2023-2610 Overview

CVE-2023-2610 is an integer overflow or wraparound vulnerability in the Vim text editor affecting versions prior to 9.0.1532. This vulnerability exists in the GitHub repository vim/vim and can be triggered when expanding the tilde (~) character in substitute operations, potentially causing very long text that leads to a crash. The integer overflow occurs in the regtilde() function within src/regexp.c, where improper handling of text length calculations can result in memory corruption.

Critical Impact

This integer overflow vulnerability in Vim can allow attackers to achieve arbitrary code execution with the privileges of the user running Vim through crafted substitute operations. Successful exploitation requires user interaction to open a malicious file or execute a crafted command.

Affected Products

• Vim versions prior to 9.0.1532
• Apple macOS systems bundling affected Vim versions (addressed in HT213844, HT213845)
• Debian, Fedora, and other Linux distributions with vulnerable Vim packages

Discovery Timeline

• 2023-05-09 - CVE-2023-2610 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2023-2610

Vulnerability Analysis

The vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). It manifests in the regtilde() function in src/regexp.c, which handles the expansion of the tilde character in substitute commands. The function failed to properly validate length calculations when processing substitute patterns containing tilde expansion, leading to an integer overflow condition.

When a user executes a substitute command with specific patterns that cause excessive tilde expansion, the resulting text length can exceed the maximum value that can be stored in an integer variable. This wraparound causes incorrect memory allocation sizes, leading to heap buffer overflows and potential arbitrary code execution.

The attack requires local access and user interaction—specifically, the victim must open a maliciously crafted file or execute a Vim command that triggers the vulnerable code path. Upon successful exploitation, an attacker can achieve high impact to confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause is improper integer handling in the regtilde() function within src/regexp.c. The function previously used integer variables (len, prevlen) to track text lengths without adequate overflow checks. When processing substitute patterns with extensive tilde expansion, these length calculations could overflow, resulting in undersized buffer allocations and subsequent memory corruption.

The patch removes the vulnerable integer length tracking variables and implements safer text handling to prevent the overflow condition from occurring.

Attack Vector

The attack vector is local, requiring the attacker to convince a user to open a specially crafted file or execute a malicious Vim command. The exploitation scenario involves:

1. Attacker crafts a file containing substitute commands with tilde patterns designed to trigger integer overflow
2. Victim opens the file in Vim or sources it as a script
3. The regtilde() function processes the malicious substitute pattern
4. Integer overflow occurs during length calculation
5. Memory corruption leads to crash or potential code execution

// Patch from src/regexp.c - removes vulnerable length tracking variables
// Source: https://github.com/vim/vim/commit/ab9a2d884b3a4abe319606ea95a5a6d6b01cd73a

 regtilde(char_u *source, int magic)
 {
     char_u	*newsub = source;
-    char_u	*tmpsub;
     char_u	*p;
-    int		len;
-    int		prevlen;
 
     for (p = newsub; *p; ++p)
     {

Source: GitHub Commit Changes

Detection Methods for CVE-2023-2610

Indicators of Compromise

• Vim process crashes or unexpected termination during substitute operations
• Core dumps associated with the regtilde() function or regexp processing
• Suspicious Vim script files containing unusual substitute patterns with repeated tilde characters
• Memory access violations reported in system logs related to Vim execution

Detection Strategies

• Monitor for Vim crashes with stack traces pointing to regexp.c or regtilde() function
• Implement file integrity monitoring on systems with Vim installed to detect version tampering
• Use package management tools to audit installed Vim versions against known vulnerable versions (prior to 9.0.1532)
• Deploy endpoint detection rules to flag unusual Vim script execution patterns

Monitoring Recommendations

• Enable crash reporting and core dump collection for Vim processes on critical systems
• Monitor software inventory for outdated Vim installations across the environment
• Review security advisories from Debian, Fedora, Apple, and other vendors for patch availability
• Implement application allowlisting to control which Vim scripts can be executed

How to Mitigate CVE-2023-2610

Immediate Actions Required

• Update Vim to version 9.0.1532 or later immediately on all affected systems
• Apply vendor-specific security patches from Debian, Fedora, Apple, or your Linux distribution
• Restrict execution of untrusted Vim scripts or files from unknown sources
• Consider temporarily using alternative text editors for processing untrusted content

Patch Information

The vulnerability has been addressed in Vim version 9.0.1532. The fix is available via the GitHub Commit (commit hash: ab9a2d884b3a4abe319606ea95a5a6d6b01cd73a). Multiple vendors have released patches:

• Apple: Security updates HT213844 and HT213845
• Debian: LTS Announcement
• Fedora: Package Announcement
• NetApp: Security Advisory

Workarounds

• Avoid opening files from untrusted sources in Vim until patched
• Disable execution of Vim modelines by adding set nomodeline to your .vimrc configuration
• Run Vim in restricted mode (vim -Z) when editing potentially malicious files
• Use container isolation or sandboxing when processing untrusted content with Vim

# Configuration example - Add to ~/.vimrc to reduce attack surface
# Disable modeline processing (prevents automatic command execution)
set nomodeline

# Verify Vim version meets minimum safe version
vim --version | head -n 1
# Should show version 9.0.1532 or later