CVE-2026-29050 melange has Path Traversal When Resolving External Pipelines via Unvalidated pipeline[].uses
Attackers can execute arbitrary shell commands and read files by manipulating pipeline paths in melange configuration files during builds.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-29050?
CVE-2026-29050 is a medium-severity path traversal vulnerability in chainguard-dev melange, published on 23 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
melange allows users to build apk packages using declarative pipelines. Starting in version 0.32.0 and prior to version 0.43.4, an attacker who can influence a melange configuration file — for example through pull-request-driven CI or build-as-a-service scenarios — could set `pipeline[].uses` to a value containing `../` sequences or an absolute path. The `(*Compiled).compilePipeline` function in `pkg/build/compile.go` passed `uses` directly to `filepath.Join(pipelineDir, uses + ".yaml")` without validating the value, so the resolved path could escape each `--pipeline-dir` and read an arbitrary YAML-parseable file visible to the melange process. Because the loaded file is subsequently interpreted as a melange pipeline and its `runs:` block is executed via `/bin/sh -c` in the build sandbox, this additionally allowed shell commands sourced from an out-of-tree file to run during the build, bypassing the review boundary that normally covers the in-tree pipeline definition. The issue is fixed in melange v0.43.4 via commit 5829ca4. The fix rejects `uses` values that are absolute paths or contain `..`, and verifies (via `filepath.Rel` after `filepath.Clean`) that the resolved target remains within the pipeline directory. As a workaround, only run `melange build` against configuration files from trusted sources. In CI systems that build user-supplied melange configs, gate builds behind manual review of `pipeline[].uses` values and reject any containing `..` or leading `/`.
Weakness: CWE-22
Which versions are affected by CVE-2026-29050?
3 open source packages ship an affected version, including chainguard.dev/melange. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
chainguard.dev/melange Go | From 0.32.0 | 0.43.4 |
chainguard.dev/melange Go | From 0.32.0 | 0.43.4 |
chainguard.dev/melange Go | From 0.32.0 | 0.43.4 |
Products include Chainguard Melange.
How do I fix CVE-2026-29050?
Upgrade chainguard.dev/melange to 0.43.4 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-29050 being exploited?
There is no known exploitation of CVE-2026-29050 in the wild and no public exploit code.
Other vulnerabilities in chainguard-dev melange
- CVE-2026-24843 melange QEMU runner could write files outside workspace directory
- CVE-2026-24844 melange pipeline working-directory could allow command injection
- CVE-2026-25143 melange affected by potential host command execution via license-check YAML mode patch pipeline
- CVE-2026-25145 melange has a path traversal in license-path which allows reading files outside workspace
- CVE-2026-29051 melange has Path Traversal via .PKGINFO in --persist-lint-results
Sources
Also known as GHSA-98f2-w9h9-7fp9, GO-2026-5279.