CVE-2026-42795

Description

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.

References

• https://cna.erlef.org/cves/CVE-2026-42795.html
• https://github.com/gleam-lang/gleam/commit/6435a5528b9ae0449e2f32be579641ec485f6866
• https://github.com/gleam-lang/gleam/security/advisories/GHSA-qhh5-fg4c-8gqc
• https://osv.dev/vulnerability/EEF-CVE-2026-42795
• https://github.com/gleam-lang/gleam/security/advisories/GHSA-qhh5-fg4c-8gqc