CVE-2026-43965 Path Traversal in build/packages/packages.toml Allows Arbitrary Directory Deletion
Attackers can delete arbitrary directories by tricking users into downloading dependencies from a project with a malicious packages.toml file.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-43965?
CVE-2026-43965 is a medium-severity path traversal vulnerability in Gleam, published on 2 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
Path traversal vulnerability in Gleam's dependency management allows arbitrary directory deletion via malicious build/packages/packages.toml content.
Package keys read from build/packages/packages.toml by LocalPackages::read_from_disc are passed without validation to paths.build_packages_package(), which constructs a filesystem path by joining the project build directory with the attacker-controlled key. The resulting path is then passed to fs::delete_directory (which calls remove_dir_all). No check is performed to ensure the path remains within the intended build/packages/ directory. Both absolute paths and relative traversal sequences (e.g. ../) are accepted as package keys, allowing deletion of arbitrary directories.
An attacker who can cause a victim to run gleam deps download on a project containing a malicious build/packages/packages.toml (e.g. by committing the normally-gitignored file to a repository) can cause arbitrary directories on the victim's system to be recursively deleted.
This issue affects Gleam from 0.18.0-rc1 until 1.17.0.
Weakness: CWE-22
Which versions are affected by CVE-2026-43965?
How do I fix CVE-2026-43965?
Apply the vendor's patch.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-43965 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43965 exists.
Sources
Also known as EEF-CVE-2026-43965, GHSA-jqvf-f6p2-wrv3.