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.

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Fixes

Solution

Upgrade Gleam to 1.19.2 or later. Gleam then rejects a hex.pm release whose OTP application name, or the application name it gives a dependency, isn't a lowercase letter followed by lowercase letters, digits and _.


Workaround

No workaround given by the vendor.

History

Mon, 12 Oct 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Gleam
Gleam gleam
Vendors & Products Gleam
Gleam gleam

Mon, 12 Oct 2026 18:45:00 +0000

Type Values Removed Values Added
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.
Title Path traversal in Gleam via unvalidated package application names
First Time appeared Gleam-lang
Gleam-lang gleam
Weaknesses CWE-22
CPEs cpe:2.3:a:gleam-lang:gleam:*:*:*:*:*:*:*:*
Vendors & Products Gleam-lang
Gleam-lang gleam
References
Metrics cvssV4_0

{'score': 5.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-10-12T18:23:41.507Z

Reserved: 2026-10-07T13:15:01.364Z

Link: CVE-2026-103061

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-12T19:16:36.387

Modified: 2026-10-12T19:16:36.387

Link: CVE-2026-103061

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-12T21:30:17Z

Weaknesses