CVE-2022-3296: Vim Buffer Overflow Vulnerability

CVE-2022-3296 Overview

CVE-2022-3296 is a stack-based buffer overflow vulnerability in the Vim text editor affecting versions prior to 9.0.0577. The flaw resides in Vim's source code and can be triggered when a user opens or processes a specially crafted file. Successful exploitation allows an attacker to corrupt stack memory, potentially leading to arbitrary code execution within the context of the user running Vim. The vulnerability is tracked under [CWE-121] (Stack-based Buffer Overflow) and [CWE-787] (Out-of-bounds Write). Vim is shipped by default on most Linux distributions, including Fedora 35, 36, and 37, broadening the exposure footprint across enterprise Linux environments.

Critical Impact
A local attacker can achieve high-impact compromise of confidentiality, integrity, and availability by convincing a user to open a malicious file in a vulnerable Vim build.

Affected Products

Vim versions prior to 9.0.0577
Fedora 35, 36, and 37 distributions shipping the affected Vim package
Gentoo Linux systems prior to the GLSA 202305-16 update

Discovery Timeline

2022-09-25 - CVE-2022-3296 published to the National Vulnerability Database (NVD)
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-3296

Vulnerability Analysis

The vulnerability is a stack-based buffer overflow within Vim's C source code. When Vim processes specific input patterns, a fixed-size stack buffer is written past its allocated boundary. The corruption overwrites adjacent stack data, including saved return addresses and frame pointers, which an attacker can manipulate to redirect execution flow.

The issue was reported through the Huntr bug bounty platform and remediated upstream in commit 96b9bf8f74af8abf1e30054f996708db7dc285be. Because Vim is frequently invoked through editor wrappers such as vi, view, or vimdiff, even non-interactive workflows that pipe untrusted content into Vim are exposed. Modern compiler hardening such as stack canaries (-fstack-protector) and Address Space Layout Randomization (ASLR) raise the bar for reliable exploitation but do not fully eliminate risk.

Root Cause

The root cause is improper bounds checking on a fixed-length stack buffer during the processing of crafted input. The vulnerable code writes user-controlled data into the buffer without validating that the input length fits within the buffer's capacity, producing an out-of-bounds write classified as [CWE-787]. Refer to the upstream patch commit for the exact code path remediated.

Attack Vector

Exploitation requires local access and user interaction. An attacker delivers a malicious file, typically through phishing, a shared filesystem, a code repository, or a Git hook, and waits for the victim to open it in Vim. Once opened, the crafted content triggers the overflow during parsing. The vulnerability does not escalate privileges by itself; code execution occurs as the user running Vim. Detailed reproduction steps are documented in the Huntr bounty report.

Detection Methods for CVE-2022-3296

Indicators of Compromise

Unexpected child processes spawned by vim, vi, view, or vimdiff, particularly shells (/bin/sh, /bin/bash) or network utilities
Vim crash artifacts such as core dumps, SIGSEGV entries in dmesg, or audit records referencing the Vim binary
Outbound network connections originating from a Vim process, which has no legitimate need for external connectivity

Detection Strategies

Inventory installed Vim versions across Linux endpoints and flag any build below 9.0.0577
Monitor process lineage where Vim is the parent of unexpected interpreters, compilers, or reverse shell tooling
Correlate file-open events on untrusted paths (e.g., /tmp, download directories, shared mounts) with Vim execution

Monitoring Recommendations

Enable Linux audit rules on execve events for Vim binaries and centralize logs for correlation
Alert on Vim processes invoking connect(), socket(), or writing to startup directories such as ~/.bashrc or ~/.ssh/authorized_keys
Track package management activity to confirm patched Vim versions remain deployed after updates

How to Mitigate CVE-2022-3296

Immediate Actions Required

Upgrade Vim to version 9.0.0577 or later on all Linux, macOS, and Windows systems
Apply distribution updates published by Fedora and the Gentoo GLSA 202305-16 advisory
Audit shared developer workstations and build servers where Vim is invoked against untrusted source files

Patch Information

The upstream fix is included in Vim 9.0.0577 via commit 96b9bf8f74af8abf1e30054f996708db7dc285be. Fedora published updated packages in the package-announce mailing list, and Gentoo addressed the issue in GLSA 202305-16. Administrators should validate the installed Vim version after applying updates to confirm remediation.

Workarounds

Avoid opening untrusted files in Vim until the patch is applied; use cat, less, or a sandboxed viewer to inspect suspicious content
Run Vim inside a restricted environment such as a container, firejail, or bubblewrap sandbox when handling external files
Restrict execute permissions on legacy Vim binaries that cannot be promptly upgraded

bash

# Verify the installed Vim version meets the patched baseline
vim --version | head -1

# Fedora / RHEL based systems
sudo dnf upgrade --refresh vim-common vim-enhanced vim-minimal

# Gentoo systems (per GLSA 202305-16)
sudo emerge --sync && sudo emerge --ask --oneshot --verbose ">=app-editors/vim-9.0.0577"