# CVE-2026-42795: Symlink Following in Hex Package Export Allows Embedding Files Outside Project Root

> Attackers with repository write access can embed sensitive local files into published packages via symlinks, exposing secrets to consumers.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 2 Jun 2026
- **Updated:** 8 Sep 2026
- **Also known as:** EEF-CVE-2026-42795, GHSA-qhh5-fg4c-8gqc

## What is CVE-2026-42795?

CVE-2026-42795 is a medium-severity path traversal vulnerability in Gleam, published on 2 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Symlink following vulnerability in Gleam's Hex package export allows files outside the project root to be embedded in the generated package tarball.

The file collection helpers (gleam_files, native_files, private_files) in compiler-cli/src/fs.rs use follow_links(true) when walking publishable directories such as src/ and priv/. The collected paths are added to the package archive via add_path_to_tar in compiler-cli/src/publish.rs without verifying that the resolved target remains within the project root. A symlink placed under a publishable directory will cause gleam export hex-tarball or gleam publish to embed the contents of the symlink target into the generated Hex package.

An attacker with write access to the project repository can place a symlink in src/ or priv/ pointing to an arbitrary file. When a maintainer or CI pipeline runs gleam publish or gleam export hex-tarball, local files readable by the publisher (such as secrets, tokens, or SSH keys) are silently embedded into the published package artifact.

This issue affects Gleam from 0.10.0-rc1 until 1.17.0.

Weakness: CWE-59 (Improper Link Resolution Before File Access)

## Which versions are affected by CVE-2026-42795?


## How do I fix CVE-2026-42795?

Apply the vendor's patch.

## Is CVE-2026-42795 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42795 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42795 and fix it if it is affected.

What it is: CVE-2026-42795 is a medium-severity path traversal vulnerability in Gleam, published on 2 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42795 exists.

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-2026-42795/ (Markdown: https://insights.sbomify.com/CVE-2026-42795/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42795
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42795
- OSV: https://osv.dev/vulnerability/CVE-2026-42795

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42795/
Summaries are generated and may contain mistakes; the official description above is the record.