CVE-2026-103061 Path traversal in Gleam via unvalidated package application names
A malicious package publisher can delete arbitrary directories outside the build folder when a developer builds a project using the Gleam compiler.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-103061?
CVE-2026-103061 is a medium-severity path traversal vulnerability in Gleam, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
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.
Weakness: CWE-22
Which versions are affected by CVE-2026-103061?
How do I fix CVE-2026-103061?
No fix has been published for CVE-2026-103061 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-103061 being exploited?
There is no known exploitation of CVE-2026-103061 in the wild and no public exploit code.
Sources
Also known as EEF-CVE-2026-103061, GHSA-jhcr-c7qm-8589.