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Description

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.

PUBLISHED Reserved 2026-05-04 | Published 2026-06-02 | Updated 2026-06-02 | Assigner EEF




MEDIUM: 5.6CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Product status

Default status
unaffected

0.18.0-rc1 (semver) before 1.17.0
affected

Default status
unaffected

0.18.0-rc1 (semver) before 1.17.0
affected

ed7aec0484f10d60978b63788c8a6497590855ab (git) before 690ca069817bee5f77a28fc3e360627c1da19291
affected

Default status
unaffected

v0.18.0-rc1-elixir (other) before v1.17.0-elixir
affected

v0.18.0-rc1-erlang (other) before v1.17.0-erlang
affected

v0.18.0-rc1-node (other) before v1.17.0-node
affected

v0.18.0-rc1-node-slim (other) before v1.17.0-node-slim
affected

v0.18.0-rc1-elixir-slim (other) before v1.17.0-elixir-slim
affected

v0.18.0-rc1-erlang-slim (other) before v1.17.0-erlang-slim
affected

v0.18.0-rc1-erlang-alpine (other) before v1.17.0-erlang-alpine
affected

v0.18.0-rc1-elixir-alpine (other) before v1.17.0-elixir-alpine
affected

v0.18.0-rc1-node-alpine (other) before v1.17.0-node-alpine
affected

v0.18.0-rc1-scratch (other) before v1.17.0-scratch
affected

Credits

Aly (spect3r1) finder

Abdelrahman Ahmed Aboelkasem (0x2face) finder

Louis Pilfold remediation developer

Jonatan Männchen / EEF analyst

References

github.com/.../gleam/security/advisories/GHSA-jqvf-f6p2-wrv3 exploit

github.com/.../gleam/security/advisories/GHSA-jqvf-f6p2-wrv3 vendor-advisory related

cna.erlef.org/cves/CVE-2026-43965.html related

osv.dev/vulnerability/EEF-CVE-2026-43965 related

github.com/...ommit/690ca069817bee5f77a28fc3e360627c1da19291 patch

cve.org (CVE-2026-43965)

nvd.nist.gov (CVE-2026-43965)

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