Executive brief
Environment Modules is a software tool that manages user environment variables and shell configurations in enterprise systems. A local attacker can place a maliciously crafted module file in a shared directory, which gets executed as a shell command when another user invokes Bash completion for module commands, allowing the attacker to run arbitrary commands with the victim's privileges and access their data or disrupt their work.
Technical details
The vulnerability is an arbitrary command execution flaw in Environment Modules' Bash completion script. The root cause is insufficient input validation and sanitization of module names that contain shell metacharacters. When a user invokes shell completion for the `module` or `ml` command, the completion script evaluates module names found in directories listed in the `MODULEPATH` environment variable without proper escaping. An attacker who can write to a location in `MODULEPATH` can create a module file with a name containing shell metacharacters (e.g., backticks, `$()`, pipes), which are then executed in the user's shell context during completion. The attack vector is local, requiring write access to a shared module directory. A patch should be applied to properly escape or validate module names before they are used in shell completion contexts.
Affected products
- Environment Modules Environment Modules unknown
Timeline
- 2026-09-15: disclosed