Vulnerability · Published Jun 2, 2026 · Assigned by EEF
CVE-2026-43965Path Traversal in build/packages/packages.toml Allows Arbitrary Directory Deletion
Medium 5.6
In plain English
A medium-severity path traversal in Gleam from Gleam. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Gleam | Gleam | 0.18.0-rc1 – before 1.17.0 |
| Gleam | Gleam | 0.18.0-rc1 – before 1.17.0ed7aec0484f10d60978b63788c8a6497590855ab – before 690ca069817bee5f77a28fc3e360627c1da19291 |
| Gleam | Gleam | v0.18.0-rc1-elixir – before v1.17.0-elixirv0.18.0-rc1-erlang – before v1.17.0-erlangv0.18.0-rc1-node – before v1.17.0-nodev0.18.0-rc1-node-slim – before v1.17.0-node-slimv0.18.0-rc1-elixir-slim – before v1.17.0-elixir-slimv0.18.0-rc1-erlang-slim – before v1.17.0-erlang-slimv0.18.0-rc1-erlang-alpine – before v1.17.0-erlang-alpinev0.18.0-rc1-elixir-alpine – before v1.17.0-elixir-alpine |
Weakness: CWE-22 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N