CVE-2026-96612: Path traversal in Hex via unvalidated dependency app names
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in hexpm hex allows a malicious package publisher to delete a directory outside the project's deps directory and extract package files into it when a developer fetches dependencies.
A package release's requirements carry an app label that names the dependency's OTP application. Hex takes this label from the repository's signed registry and uses it as the dependency's application name without validating it (Hex.RemoteConverger.deps/2, Hex.Mix.tolock/1). Mix derives the dependency's checkout directory as deps/<app>, and Hex.SCM.update/1 runs File.rmrf!/1 on that directory and unpacks the package into it. hex.pm only checks the label's length, so a publisher can set it to a value such as ../../target. When a project depends on such a release directly or transitively, mix deps.get or mix deps.update deletes the directory the label resolves to and writes the labelled package's files there. This happens before any dependency code is compiled.
This issue affects hex: from 0.6.0 before 2.5.2.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
hexto a version that resolves this vulnerability.Fixed in 2.5.2
Event History
Frequently Asked Questions
Which projects are exposed to this issue?
Projects using Hex versions from 0.6.0 before 2.5.2 are affected if they fetch a package release whose direct or transitive dependency requirements contain a malicious application label. The issue is triggered during mix deps.get or mix deps.update.
What does an attacker need to exploit it?
An attacker needs to publish a package release with a dependency requirement whose OTP application label contains a traversal value such as ../../target. A developer must then fetch that release, either directly or through a transitive dependency.
Does exploitation require dependency code to be compiled or run?
No. Hex removes the resolved checkout directory and extracts package files into it while fetching dependencies, before dependency code is compiled.
What is the impact on the developer machine or build environment?
The malicious label can cause Hex to delete a directory outside the project's deps directory and extract package files into that external location. The affected directory is determined by the traversal path in the application label.
What version resolves the issue?
Upgrade Hex to version 2.5.2 or later. Versions before 2.5.2, starting with 0.6.0, are affected.