CVE-2007-2953

Vulnerability

A format string vulnerability exists in the helptags_one function in src/ex_cmds.c of Vim. Versions 6.4 and earlier, and 7.x up to 7.1 (including 7.0 and 7.1 before patch 7.1.039), are affected [2][3]. The flaw is triggered when the helptags command processes a help file that contains a help-tags tag with embedded format string specifiers. This occurs because the tag content is passed directly to a format string function without proper sanitization [2].

Exploitation

An attacker must craft a malicious help file containing a help-tags tag with format string specifiers (e.g., %n or %x) and then convince a user to run the helptags command on that file. The attacker does not require any network access or authentication; however, direct user interaction is necessary, making this a user-assisted attack scenario [2][3]. The user might be tricked via social engineering (e.g., opening a downloaded archive and executing the command). The helptags command is typically used to generate tag files for help documentation; no special privileges are needed to invoke it.

Impact

Successful exploitation allows an attacker to execute arbitrary code with the permissions of the user running Vim [2]. This can lead to full compromise of the user's system, including data theft, installation of malware, or further lateral movement within the network. The impact is limited to the user's privileges and does not inherently escalate to root or system-level access.

Mitigation

Vim fixed this issue in patch 7.1.039 (released around August 2007) [3]. Users are advised to upgrade to Vim 7.1.039 or later. For systems where upgrading is not immediately possible, avoiding the use of the helptags command on untrusted help files is recommended as a workaround. Red Hat released RHSA-2008-0617 to address this and other Vim vulnerabilities [4]. VMware also addressed this in ESX service console updates as part of VMSA-2009-0004 [1].