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.
" } ], "value": "Symlink following vulnerability in Gleam's Hex package export allows files outside the project root to be embedded in the generated package tarball.\n\nThe 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.\n\nAn 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.\n\nThis issue affects Gleam from 0.10.0-rc1 until 1.17.0." } ], "impacts": [ { "capecId": "CAPEC-132", "descriptions": [ { "lang": "en", "value": "CAPEC-132 Symlink Attack" } ] } ], "metrics": [ { "cvssV4_0": { "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "LOCAL", "baseScore": 5.1, "baseSeverity": "MEDIUM", "privilegesRequired": "LOW", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "ACTIVE", "vectorString": "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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "NONE" }, "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ] } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-59", "description": "CWE-59 Improper Link Resolution Before File Access ('Link Following')", "lang": "en", "type": "CWE" } ] } ], "providerMetadata": { "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-06-02T19:14:25.176Z" }, "references": [ { "tags": [ "vendor-advisory", "related" ], "url": "https://github.com/gleam-lang/gleam/security/advisories/GHSA-qhh5-fg4c-8gqc" }, { "tags": [ "related" ], "url": "https://cna.erlef.org/cves/CVE-2026-42795.html" }, { "tags": [ "related" ], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-42795" }, { "tags": [ "patch" ], "url": "https://github.com/gleam-lang/gleam/commit/6435a5528b9ae0449e2f32be579641ec485f6866" } ], "source": { "discovery": "EXTERNAL" }, "title": "Symlink Following in Hex Package Export Allows Embedding Files Outside Project Root", "workarounds": [ { "lang": "en", "supportingMedia": [ { "base64": false, "type": "text/html", "value": "