Heap-based Buffer Overflow in vim/vim

Vulnerability

A heap-based buffer overflow vulnerability exists in the Vim text editor prior to version 8.2. The flaw is triggered during the processing of certain commands, particularly when a cmdline window is opened from a substitute expression [2]. The patch for this issue is identified as patch 8.2.5043, which introduces checks like text_locked and refactors locking functions to prevent unsafe operations [2].

Exploitation

An attacker can exploit this vulnerability by crafting a malicious file or input that, when opened or processed by Vim, triggers the heap-based buffer overflow. The attacker does not require authentication but relies on user interaction—the victim must open the crafted file or trigger the substitute expression in Vim [1][2]. The exact step involves the use of getcmdline and related functions that fail to properly validate buffer boundaries before writing data.

Impact

Successful exploitation leads to arbitrary code execution in the context of the Vim process. This could allow an attacker to execute arbitrary commands, potentially gaining control of the system [1]. The impact is severe, as Vim is widely used across servers and development environments.

Mitigation

Users should upgrade to Vim version 8.2.5043 or later, released in the commit [2]. For downstream distributions, Apple included the fix in macOS Ventura 13 [1], and Gentoo provides updated packages (>=app-editors/vim-9.0.0060) [4]. No workaround is available if an upgrade is not possible [4].