# 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.

- **Severity:** Medium 5.9 (`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`)
- **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 available:** No
- **Published:** 12 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** EEF-CVE-2026-103061, GHSA-jhcr-c7qm-8589

## 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 (Improper Limitation of a Pathname to a Restricted Directory)

## 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.

## Is CVE-2026-103061 being exploited?

There is no known exploitation of CVE-2026-103061 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103061 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-103061 in the wild and no public exploit code.

Affected product: Gleam. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-103061/ (Markdown: https://insights.sbomify.com/CVE-2026-103061/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103061
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103061
- OSV: https://osv.dev/vulnerability/CVE-2026-103061

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103061/
Summaries are generated and may contain mistakes; the official description above is the record.