CVE-2026-103061: Path traversal in Gleam via unvalidated package application names

Official description

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in gleam-lang gleam allows a malicious package publisher to delete a directory outside the project's build directory when a developer builds a project. A Hex package release's metadata carries an app field with the release's OTP application name. Gleam reads this field from the hex.pm release API when it downloads dependencies and uses it as the package's build directory name without validating it (hex_manifest_package in compiler-cli/src/dependencies.rs, ProjectPaths::build_directory_for_package). When a dependency fails to compile, Gleam deletes that directory with remove_dir_all. hex.pm didn't restrict the field to a directory name before 2026-10-12, so a publisher could set it to a value such as ../../../../target or an absolute path. When a project depends on such a release directly or transitively and the release fails to compile, gleam build, gleam check, gleam run, gleam test or gleam export deletes the directory the name resolves to. For a pure Gleam package no publisher code runs. This issue affects gleam: from 0.32.4 before 1.19.2.

Affected products (as reported)

Vendor	Product	Versions
Gleam	Gleam	0.32.4 – before 1.19.2
Gleam	Gleam	v0.32.4-elixir – before v1.19.2-elixirv0.32.4-erlang – before v1.19.2-erlangv0.32.4-node – before v1.19.2-nodev0.32.4-node-slim – before v1.19.2-node-slimv0.32.4-elixir-slim – before v1.19.2-elixir-slimv0.32.4-erlang-slim – before v1.19.2-erlang-slimv0.32.4-erlang-alpine – before v1.19.2-erlang-alpinev0.32.4-elixir-alpine – before v1.19.2-elixir-alpine
Gleam	Gleam	d13f27ee80aae7a521d2e9433c4deaf53f892574 – before *

CVE-2026-103061Path traversal in Gleam via unvalidated package application names

In plain English

Official description

Affected products (as reported)

References