Gleam up to 1.16.x packages.toml paths.build_packages_package path traversal

CVSS Meta Temp Score
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CTI Interest Score
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3.2$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Gleam up to 1.16.x. The affected element is the function paths.build_packages_package of the file build/packages/packages.toml. This manipulation causes path traversal. This vulnerability is registered as CVE-2026-43965. The attack needs to be launched locally. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Gleam up to 1.16.x. It has been declared as problematic. Affected by this vulnerability is the function paths.build_packages_package of the file build/packages/packages.toml. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect availability. The summary by CVE is:

Path traversal vulnerability in Gleam's dependency management allows arbitrary directory deletion via malicious build/packages/packages.toml content. Package keys read from build/packages/packages.toml by LocalPackages::read_from_disc are passed without validation to paths.build_packages_package(), which constructs a filesystem path by joining the project build directory with the attacker-controlled key. The resulting path is then passed to fs::delete_directory (which calls remove_dir_all). No check is performed to ensure the path remains within the intended build/packages/ directory. Both absolute paths and relative traversal sequences (e.g. ../) are accepted as package keys, allowing deletion of arbitrary directories. An attacker who can cause a victim to run gleam deps download on a project containing a malicious build/packages/packages.toml (e.g. by committing the normally-gitignored file to a repository) can cause arbitrary directories on the victim's system to be recursively deleted. This issue affects Gleam from 0.18.0-rc1 until 1.17.0.

The weakness was published by Aly as GHSA-jqvf-f6p2-wrv3. The advisory is shared at github.com. This vulnerability is known as CVE-2026-43965 since 05/04/2026. The exploitation appears to be easy. An attack has to be approached locally. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1006 for this issue.

Upgrading to version 1.17.0, 1.17.0-elixir, 1.17.0-elixir-alpine, 1.17.0-elixir-slim, 1.17.0-erlang, 1.17.0-erlang-alpine, 1.17.0-erlang-slim, 1.17.0-node, 1.17.0-node-alpine, 1.17.0-node-slim or 1.17.0-scratch eliminates this vulnerability. Applying the patch 690ca069817bee5f77a28fc3e360627c1da19291 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-33926). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 3.3
VulDB Meta Temp Score: 3.2

VulDB Base Score: 3.3
VulDB Temp Score: 3.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Path traversal
CWE: CWE-22
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Gleam 1.17.0/1.17.0-elixir/1.17.0-elixir-alpine/1.17.0-elixir-slim/1.17.0-erlang/1.17.0-erlang-alpine/1.17.0-erlang-slim/1.17.0-node/1.17.0-node-alpine/1.17.0-node-slim/1.17.0-scratch
Patch: 690ca069817bee5f77a28fc3e360627c1da19291

Timelineinfo

05/04/2026 CVE reserved
06/02/2026 +29 days Advisory disclosed
06/02/2026 +0 days VulDB entry created
06/02/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-jqvf-f6p2-wrv3
Researcher: Aly
Status: Confirmed

CVE: CVE-2026-43965 (🔒)
GCVE (CVE): GCVE-0-2026-43965
GCVE (VulDB): GCVE-100-367945
EUVD: 🔒

Entryinfo

Created: 06/02/2026 17:17
Updated: 06/02/2026 23:42
Changes: 06/02/2026 17:17 (71), 06/02/2026 23:42 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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