Weakness Type (CWE)

CWE-59 — CWE-59 Improper Link Resolution Before File Access ('Link Following')

CAPEC

CVSS 4.0 Score

5.1

MEDIUM

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

Vulnerability 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.

Affected

pkg:sid/gleam.run/gleam

Module Source File Routine
compiler-cli compiler-cli/src/fs.rs compiler_cli::fs::gleam_files
compiler-cli/src/publish.rs compiler_cli::fs::native_files
compiler_cli::fs::private_files
compiler_cli::publish::project_files
compiler_cli::publish::add_path_to_tar
Status Type Version Changes / Fixed in
affected semver ⓘ 0.10.0-rc1 < 1.17.0

pkg:github/gleam-lang/gleam

Module Source File Routine
compiler-cli compiler-cli/src/fs.rs compiler_cli::fs::gleam_files
compiler-cli/src/publish.rs compiler_cli::fs::native_files
compiler_cli::fs::private_files
compiler_cli::publish::project_files
compiler_cli::publish::add_path_to_tar
Status Type Version Changes / Fixed in
affected semver ⓘ 0.10.0-rc1 < 1.17.0
affected git ⓘ c82a2d83bd < 6435a5528b

pkg:oci/gleam

Module Source File Routine
compiler-cli compiler-cli/src/fs.rs compiler_cli::fs::gleam_files
compiler-cli/src/publish.rs compiler_cli::fs::native_files
compiler_cli::fs::private_files
compiler_cli::publish::project_files
compiler_cli::publish::add_path_to_tar
Status Type Version Changes / Fixed in
affected other v0.10.0-rc1-elixir < v1.17.0-elixir
affected other v0.10.0-rc1-erlang < v1.17.0-erlang
affected other v0.10.0-rc1-node < v1.17.0-node
affected other v0.10.0-rc1-node-slim < v1.17.0-node-slim
affected other v0.10.0-rc1-elixir-slim < v1.17.0-elixir-slim
affected other v0.10.0-rc1-erlang-slim < v1.17.0-erlang-slim
affected other v0.10.0-rc1-erlang-alpine < v1.17.0-erlang-alpine
affected other v0.10.0-rc1-elixir-alpine < v1.17.0-elixir-alpine
affected other v0.10.0-rc1-node-alpine < v1.17.0-node-alpine
affected other v0.10.0-rc1-scratch < v1.17.0-scratch

Workarounds

  • Avoid running gleam publish or gleam export hex-tarball on untrusted projects
  • Review the contents of src/ and priv/ for unexpected symlinks before publishing
  • Run publishing commands in a restricted or isolated environment (e.g. containers)

References

Credits

  • Finder: Aly (spect3r1)
  • Finder: Abdelrahman Ahmed Aboelkasem (0x2face)
  • Remediation developer: Louis Pilfold
  • Analyst: Jonatan Männchen / EEF

CVE record as JSON:  GET /cves/CVE-2026-42795.json
OSV record as JSON:  GET /osv/EEF-CVE-2026-42795.json