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Gleam vulnerability

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.

Published 2 Jun 2026Updated 7 Sep 20265 sources
CVSS 5.1
Overview Sources History

What happened

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.

Affected versions

Gleam: 0.10.0-rc1 through before 1.17.0 (semver); c82a2d83bd0c06cafdc196820deb3f89a9b3ff7c through before 6435a5528b9ae0449e2f32be579641ec485f6866 (git); v0.10.0-rc1-elixir through before v1.17.0-elixir (other); v0.10.0-rc1-erlang through before v1.17.0-erlang (other); v0.10.0-rc1-node through before v1.17.0-node (other); v0.10.0-rc1-node-slim through before v1.17.0-node-slim (other); v0.10.0-rc1-elixir-slim through before v1.17.0-elixir-slim (other); v0.10.0-rc1-erlang-slim through before v1.17.0-erlang-slim (other); v0.10.0-rc1-erlang-alpine through before v1.17.0-erlang-alpine (other); v0.10.0-rc1-elixir-alpine through before v1.17.0-elixir-alpine (other); v0.10.0-rc1-node-alpine through before v1.17.0-node-alpine (other); v0.10.0-rc1-scratch through before v1.17.0-scratch (other) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.

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