CVE-2025-1215: Vim Buffer Overflow Vulnerability

CVE-2025-1215 Overview

A memory corruption vulnerability was discovered in Vim text editor versions up to 9.1.1096. This vulnerability affects the src/main.c file and is triggered through manipulation of the --log command-line argument. When a non-existent path is provided to the --log argument, improper initialization of memory structures leads to a crash condition, allowing local attackers to cause denial of service.

Critical Impact

Local attackers can cause Vim to crash by providing a malformed or non-existent path to the --log argument, potentially disrupting development workflows and automated processes that depend on Vim.

Affected Products

• Vim versions up to 9.1.1096
• NetApp Bootstrap OS (incorporating affected Vim versions)

Discovery Timeline

• 2025-02-12 - CVE-2025-1215 published to NVD
• 2025-08-13 - Last updated in NVD database

Technical Details for CVE-2025-1215

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists in Vim's argument parsing logic where the --log option is processed before proper memory initialization occurs. When a user specifies a log file path that does not exist or is otherwise invalid, the application attempts to access memory structures that have not been properly initialized, resulting in memory corruption and subsequent application crash.

The vulnerability requires local access to exploit, as the attacker must be able to invoke Vim with the malicious command-line argument. User interaction is required since a legitimate user must execute or be tricked into executing Vim with the crafted arguments.

Root Cause

The root cause lies in the initialization sequence within src/main.c. Prior to the fix, certain common initialization routines were not executed before the --log and --startuptime arguments were processed. This created a race condition where log file handling code could execute before the necessary memory structures were allocated and initialized.

The patch introduces common_init_1() as an early initialization function that runs before argument parsing begins, ensuring all required memory structures are properly set up before any file operations are attempted.

Attack Vector

The attack requires local access to the system where Vim is installed. An attacker must be able to execute Vim with crafted command-line arguments. The attack scenario involves:

1. Attacker gains access to a local system with vulnerable Vim installation
2. Attacker executes Vim with --log argument pointing to a non-existent or invalid path
3. Vim crashes due to memory corruption during argument processing
4. This can be leveraged for denial of service against automated systems or scripts using Vim

// Security patch - Source: GitHub Commit c5654b84480822817bb7b69ebc97c174c91185e9
    atexit(vim_mem_profile_dump);
#endif

+    /*
+     * Various initialisations #1 shared with tests.
+     */
+    common_init_1();

#if defined(STARTUPTIME) || defined(FEAT_JOB_CHANNEL)
    // Need to find "--startuptime" and "--log" before actually parsing
    // arguments.

The patch adds an early call to common_init_1() before any argument processing occurs, ensuring memory structures are properly initialized.

Detection Methods for CVE-2025-1215

Indicators of Compromise

• Unexpected Vim crashes with core dumps or segmentation fault errors
• System logs showing Vim process terminations related to memory access violations
• Presence of scripts or commands invoking Vim with unusual --log arguments pointing to invalid paths

Detection Strategies

• Monitor for abnormal Vim process crashes, particularly those involving command-line argument processing
• Implement process monitoring to detect Vim invocations with suspicious --log arguments
• Review system logs for repeated Vim crash patterns that could indicate exploitation attempts

Monitoring Recommendations

• Configure crash monitoring tools to alert on Vim segmentation faults or memory access violations
• Audit shell history and command logs for Vim commands using the --log argument with unusual paths
• Deploy endpoint detection solutions to monitor for process crashes indicative of exploitation

How to Mitigate CVE-2025-1215

Immediate Actions Required

• Upgrade Vim to version 9.1.1097 or later immediately
• For systems where immediate upgrade is not possible, avoid using the --log command-line argument
• Review and update any automated scripts or CI/CD pipelines that invoke Vim with command-line arguments

Patch Information

The vulnerability has been addressed in Vim version 9.1.1097. The fix is available in commit c5654b84480822817bb7b69ebc97c174c91185e9. The patch refactors the initialization sequence by splitting common_init() into common_init_1() and common_init_2(), ensuring critical memory initialization occurs before argument parsing.

For additional details, refer to the GitHub Issue Discussion, GitHub Release Note for v9.1.1097, and the NetApp Security Advisory.

Workarounds

• Avoid using the --log command-line argument until the system is patched
• Ensure log paths are validated and exist before invoking Vim with --log
• Restrict local user access to prevent unauthorized execution of Vim with malicious arguments

# Verify Vim version and upgrade if necessary
vim --version | head -n 1

# On Debian/Ubuntu systems
sudo apt update && sudo apt install vim

# On RHEL/CentOS systems
sudo yum update vim

# On macOS with Homebrew
brew upgrade vim