Symlink Following in Hex Package Export Allows Embedding Files Outside Project Root

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Summary

CVECVE-2026-42795
StatePUBLISHED
AssignerEEF
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-02 14:16:53 UTC
Updated2026-06-02 16:16:40 UTC
DescriptionSymlink 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.

Risk And Classification

Primary CVSS: v4.0 5.1 MEDIUM from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-59 | CWE-59 CWE-59 Improper Link Resolution Before File Access ('Link Following')

VersionSourceTypeScoreSeverityVector
4.06b3ad84c-e1a6-4bf7-a703-f496b71e49dbSecondary5.1MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS5.1MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
Active
Confidentiality
High
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Gleam Gleam affected 0.10.0-rc1 1.17.0 semver Not specified
CNA Gleam Gleam affected 0.10.0-rc1 1.17.0 semver Not specified
CNA Gleam Gleam affected c82a2d83bd0c06cafdc196820deb3f89a9b3ff7c 6435a5528b9ae0449e2f32be579641ec485f6866 git Not specified
CNA Gleam Gleam affected v0.10.0-rc1-elixir v1.17.0-elixir other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-erlang v1.17.0-erlang other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-node v1.17.0-node other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-node-slim v1.17.0-node-slim other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-elixir-slim v1.17.0-elixir-slim other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-erlang-slim v1.17.0-erlang-slim other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-erlang-alpine v1.17.0-erlang-alpine other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-elixir-alpine v1.17.0-elixir-alpine other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-node-alpine v1.17.0-node-alpine other Not specified
CNA Gleam Gleam affected v0.10.0-rc1-scratch v1.17.0-scratch other Not specified

References

ReferenceSourceLinkTags
github.com/gleam-lang/gleam/commit/6435a5528b9ae0449e2f32be579641ec485f6866 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
github.com/gleam-lang/gleam/security/advisories/GHSA-qhh5-fg4c-8gqc 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
cna.erlef.org/cves/CVE-2026-42795.html 6b3ad84c-e1a6-4bf7-a703-f496b71e49db cna.erlef.org
osv.dev/vulnerability/EEF-CVE-2026-42795 6b3ad84c-e1a6-4bf7-a703-f496b71e49db osv.dev
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Aly (spect3r1) (en)

CNA: Abdelrahman Ahmed Aboelkasem (0x2face) (en)

CNA: Louis Pilfold (en)

CNA: Jonatan Männchen / EEF (en)

Additional Advisory Data

Workarounds

CNA: * 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)

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