Vim CVE-2026-39881

The CVSS 5.0 score reflects a localized attack vector (AV:L), high attack complexity (AC:H), and requirement for low user privileges and user interaction (PR:L/UI:R), resulting in low confidentiality impact but high integrity impact. However, the real-world risk is moderate: exploitation requires an attacker to control a malicious netbeans server and convince a local user to connect Vim to it-a restrictive precondition. The attack complexity is high because it depends on successful social engineering or network positioning. No KEV status (active exploitation by CISA) or public proof-of-concept is indicated in the provided data, suggesting this is not yet widely exploited in practice. The command injection nature (CWE-94) and ability to execute arbitrary Ex commands represent significant integrity risk if exploitation occurs, but the strict authentication and interaction requirements limit the practical threat surface compared to higher-severity remote vulnerabilities. Organizations with Vim users accepting netbeans connections from untrusted sources should prioritize patching; others can defer to regular update cycles.

An attacker sets up a malicious netbeans server and convinces a local user to connect Vim to it (via a crafted network configuration or social engineering). When Vim connects, the attacker sends a specially crafted defineAnnoType or specialKeys message containing Ex command metacharacters. The netbeans interface parser fails to escape or validate these strings, causing the injected Ex commands to execute within Vim's context with the user's privileges, potentially enabling arbitrary file manipulation, code execution, or data exfiltration depending on the injected commands and the user's file system permissions.