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Gleam vulnerability

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.

Published 2 Jun 2026Updated 7 Sep 20265 sources
CVSS 5.6
Overview Sources History

What happened

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 versions

Gleam: 0.18.0-rc1 through before 1.17.0 (semver); ed7aec0484f10d60978b63788c8a6497590855ab through before 690ca069817bee5f77a28fc3e360627c1da19291 (git); v0.18.0-rc1-elixir through before v1.17.0-elixir (other); v0.18.0-rc1-erlang through before v1.17.0-erlang (other); v0.18.0-rc1-node through before v1.17.0-node (other); v0.18.0-rc1-node-slim through before v1.17.0-node-slim (other); v0.18.0-rc1-elixir-slim through before v1.17.0-elixir-slim (other); v0.18.0-rc1-erlang-slim through before v1.17.0-erlang-slim (other); v0.18.0-rc1-erlang-alpine through before v1.17.0-erlang-alpine (other); v0.18.0-rc1-elixir-alpine through before v1.17.0-elixir-alpine (other); v0.18.0-rc1-node-alpine through before v1.17.0-node-alpine (other); v0.18.0-rc1-scratch through before v1.17.0-scratch (other) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.

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