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":{"dateUpdated":"2026-06-02T13:41:39.527Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"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":"