CVE-2025-27423 is a command injection vulnerability affecting the widely used open-source text editor Vim, specifically its tar.vim plugin. This plugin facilitates the editing and viewing of tar archives, both compressed and uncompressed, directly within Vim. Starting with version 9.1.0858, the tar.vim plugin uses the ":read" ex command to append content below the cursor position when opening tar files. However, the input taken from the tar archive is not properly sanitized before being passed to the shell, allowing an attacker to craft malicious tar archives containing special shell command elements. When such a malicious archive is opened in a vulnerable Vim version (prior to 9.1.1164), the embedded shell commands can be executed in the context of the user running Vim. The actual exploitation depends on the shell environment configured via the 'shell' option or the $SHELL environment variable. This vulnerability is categorized under CWE-77 (Improper Neutralization of Special Elements used in a Command), indicating that unsanitized input is directly used in command execution. The vulnerability has a CVSS 3.1 base score of 7.1 (high severity), with an attack vector of local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), but requires user interaction (UI:R). The impact affects confidentiality and integrity but not availability. No known exploits in the wild have been reported as of the publication date (March 3, 2025). The issue was fixed in Vim patch version 9.1.1164. The vulnerability is significant because Vim is a popular editor across many Unix-like systems, including Linux distributions and macOS, often used by developers and system administrators. The risk arises when users open malicious tar archives with vulnerable Vim versions, potentially leading to arbitrary command execution under their user privileges.

For European organizations, the impact of CVE-2025-27423 can be substantial, especially in environments where Vim is used extensively for development, system administration, or automation tasks. Successful exploitation could allow attackers to execute arbitrary shell commands, leading to unauthorized disclosure or modification of sensitive data (confidentiality and integrity impacts). Although the attack vector is local, the requirement for user interaction (opening a crafted tar archive) means phishing or social engineering could be used to trick users into triggering the exploit. This could be leveraged in targeted attacks against organizations handling sensitive intellectual property, critical infrastructure, or government data. Since Vim is often installed by default or widely used in Linux-based servers and workstations, the vulnerability could affect software development firms, research institutions, and public sector entities across Europe. The lack of availability impact reduces the risk of service disruption, but the potential for covert command execution poses a serious threat to system security and data integrity. Additionally, the dependency on the shell environment means that some configurations may be more vulnerable than others, complicating detection and mitigation. The absence of known exploits in the wild suggests limited current exploitation but does not preclude future attacks, especially as proof-of-concept code becomes available.

1. Immediate upgrade: European organizations should prioritize upgrading Vim to version 9.1.1164 or later, where the vulnerability is patched. This is the most effective mitigation. 2. Shell environment hardening: Restrict or standardize the shell environment used by Vim (the 'shell' option or $SHELL variable) to shells that limit command injection risk or implement stricter input validation. 3. User awareness and training: Educate users about the risks of opening untrusted tar archives, especially those received via email or downloaded from unverified sources, to reduce the likelihood of social engineering exploitation. 4. File scanning and filtering: Implement security controls that scan tar archives for suspicious content before they reach end users, using heuristic or signature-based detection to identify potentially malicious payloads. 5. Use sandboxing or containerization: Run Vim sessions in isolated environments where possible, limiting the impact of any command injection to the sandbox and preventing lateral movement or system-wide compromise. 6. Monitor logs and behavior: Deploy monitoring solutions to detect unusual shell command executions or anomalous behavior following the opening of tar files in Vim. 7. Restrict local access: Limit local user permissions and enforce the principle of least privilege to reduce the impact of any successful exploitation. 8. Patch management: Integrate this vulnerability into vulnerability management programs to ensure timely detection and remediation across all affected systems.