CVE-2026-42307: Vim Text Editor RCE Vulnerability

CVE-2026-42307 Overview

CVE-2026-42307 is an operating system command injection vulnerability [CWE-78] in the netrw standard plugin bundled with Vim, an open source command-line text editor. The flaw affects all Vim versions prior to 9.2.0383. An attacker can craft a malicious URL using the sftp:// or file:// protocol handlers and induce a user to open it in Vim. When the user opens the crafted URL, netrw passes attacker-controlled data into a shell command, resulting in arbitrary command execution with the privileges of the Vim process.

Critical Impact

Successful exploitation lets attackers execute arbitrary shell commands as the Vim user, enabling local code execution, data theft, or lateral movement on developer and server systems.

Affected Products

• Vim versions prior to 9.2.0383
• Vim netrw standard plugin (bundled with Vim)
• Systems where users open remote files via sftp:// or file:// handlers in Vim

Discovery Timeline

• 2026-05-08 - CVE-2026-42307 published to NVD
• 2026-05-14 - Last updated in NVD database

Technical Details for CVE-2026-42307

Vulnerability Analysis

The vulnerability resides in netrw, the Vim plugin that provides network-aware file browsing and editing for protocols such as scp://, sftp://, ftp://, and file://. Netrw constructs shell commands from URL components passed by the user, then invokes them through Vim's shell execution facilities. Insufficient escaping of metacharacters in the URL path or host fields allows attacker-controlled input to break out of the intended command and inject additional shell instructions.

The affected control variable g:netrw_tmpfile_escape, which previously enumerated characters to escape in temporary file names, was removed and replaced by safer construction logic in the patched release. Exploitation requires user interaction: the victim must open the crafted URL in Vim, for example by running vim 'sftp://...', by following a :edit command, or by interacting with a file-browser that hands a URL to Vim.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-78]. Netrw concatenated URL fields into shell command strings while relying on a hardcoded escape list that did not cover all dangerous metacharacters across the sftp: and file: code paths.

Attack Vector

The attack vector is local and requires user interaction. An adversary delivers a crafted URL via phishing, a project file, a README, a shared filesystem, or any channel where a developer might open the path in Vim. Once opened, the embedded shell metacharacters in the URL execute arbitrary commands as the Vim user.

// Patch excerpt: removal of g:netrw_tmpfile_escape in runtime/doc/pi_netrw.txt
//   patch 9.2.0383: [security]: runtime(netrw): shell-injection via sftp: and file:

               such as listing, file removal, etc.
                default: ssh

-  *g:netrw_tmpfile_escape*  =' &;'
-               escape() is applied to all temporary files
-               to escape these characters.
-
  *g:netrw_timefmt*         specify format string to vim's strftime().
               The default, "%c", is "the preferred date
               and time representation for the current

// Source: https://github.com/vim/vim/commit/405e2fb6d54d5653523809e2853d99d1c000a5fc

Detection Methods for CVE-2026-42307

Indicators of Compromise

• Vim process spawning unexpected child shells such as /bin/sh -c, bash -c, or cmd.exe /c with arguments containing URL fragments.
• Command-line arguments to Vim containing sftp:// or file:// URLs with shell metacharacters like `, $(, ;, &, or |.
• Outbound network connections initiated by child processes of Vim shortly after a file open operation.

Detection Strategies

• Hunt EDR process telemetry for parent process vim or gvim creating child processes other than expected helpers like ssh, scp, or sftp.
• Inspect shell history and audit logs for vim invocations with arguments matching sftp://*[;&|$]orfile://[;&|$]* patterns.
• Apply YARA or regex content rules to repository files, mail attachments, and chat exports searching for crafted netrw URLs.

Monitoring Recommendations

• Enable Linux auditd or Windows process-creation auditing for vim/gvim and forward events to a central log platform.
• Alert on Vim spawning interpreters such as python, perl, nc, or curl outside known developer workflows.
• Track Vim versions across managed endpoints and flag hosts running releases earlier than 9.2.0383.

How to Mitigate CVE-2026-42307

Immediate Actions Required

• Upgrade Vim to version 9.2.0383 or later on all workstations, build servers, and container images that ship Vim.
• Instruct users not to open untrusted URLs in Vim, especially those received from email, chat, or third-party repositories.
• Audit shared scripts and editor integrations for invocations like vim 'sftp://...' that propagate attacker-supplied URLs.

Patch Information

The issue is fixed in Vim 9.2.0383. The fix is committed in the Vim repository and documented in the project's security advisory. See the Vim 9.2.0383 release notes, the GitHub Security Advisory GHSA-85ch-p2qr-m5gx, and the upstream commit 405e2fb.

Workarounds

• Disable the netrw plugin by adding let g:loaded_netrw = 1 and let g:loaded_netrwPlugin = 1 to ~/.vimrc until Vim can be upgraded.
• Avoid passing remote URLs as command-line arguments to Vim; download files first with vetted tools such as scp or sftp and edit them locally.
• Restrict editor execution under least-privilege accounts so that successful injection cannot reach sensitive resources.

# Configuration example: disable netrw in ~/.vimrc as an interim workaround
let g:loaded_netrw       = 1
let g:loaded_netrwPlugin = 1

# Verify the installed Vim version is patched
vim --version | head -n 1
# Expected: VIM - Vi IMproved 9.2 (with patch 0383 or later)