A high-severity security flaw in the widely used Vim text editor allows attackers to execute arbitrary code on vulnerable systems by tricking users into opening specially crafted TAR archives.
Tracked as CVE-2025-27423, this vulnerability has prompted urgent patching efforts and warnings for developers and system administrators globally.
Technical Breakdown of the Vulnerability
The flaw resides in Vim’s tar.vim plugin, which enables users to view and edit contents of TAR files directly within the editor.
The vulnerability stems from a November 2024 update (commit 129a844) that added support for file permissions but failed to sanitize filenames extracted from TAR archives.
When a user opens a malicious TAR file, the plugin uses the :read command to append content below the cursor position.
Attackers can exploit this by embedding shell metacharacters or commands into filenames, which are then executed by the user’s default shell (as defined by the $SHELL environment variable).
Christian Brabandt, a Vim maintainer, confirmed the issue arises from improper escaping of filenames before they are passed to the :read command.
The exploit’s success depends on the shell configuration, with common shells like Bash or Zsh being prime targets.
Notably, the malicious filename becomes visible during file navigation, offering cautious users a chance to abort operations—a factor that slightly mitigates the risk.
Impact and Severity
Rated 7.1 on the CVSS v3.1 scale, CVE-2025-27423 enables local attackers to escalate privileges or compromise systems by leveraging user interaction.
While exploitation requires convincing a target to open a malicious TAR file, the consequences are severe: arbitrary code execution could lead to data theft, ransomware deployment, or lateral network movement.
The vulnerability affects all Vim versions from 9.1.0858 to 9.1.1163, with patches released in version 9.1.1164 on March 2, 2025. Major Linux distributions, including Debian, Fedora, and FreeBSD, have begun rolling out updates.
Mitigation and Recommendations
The Vim project urges users to immediately update to the patched version. For those unable to upgrade, workarounds include:
- Disabling the tar.vim plugin by removing or renaming tar.vim in Vim’s runtime directory.
- Avoiding TAR files from untrusted sources and using dedicated extraction tools like tar or gunzip.
- Configuring Vim to use a restricted shell or a shell with enhanced security settings.
Security researcher Ry0taK of GMO Flatt Security Inc., who discovered the flaw, emphasizes that vigilance remains critical even after patching: “Users should treat unsolicited TAR files with extreme skepticism, especially in collaborative or open-source environments”.
This incident underscores the risks of integrating archive-handling features into text editors, which often operate with user-level privileges.
The vulnerability also highlights the persistent challenge of input validation—a common weakness cited in CWE-20 and CWE-77 advisories.
As noted by cybersecurity firm SecAlerts, “Even minor code changes in legacy plugins can introduce critical vulnerabilities, necessitating rigorous testing”.
With Vim installed on millions of systems worldwide, administrators are advised to prioritize updates and educate teams on recognizing suspicious file artifacts.
Continuous monitoring tools like Vulert can further help organizations detect vulnerable installations in real time.
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