CVE-2026-29050 — melange
MEDIUMCVE-2026-29050 is a medium-severity (CVSS 6.1) Path Traversal vulnerability in chainguard.dev/melange. A fix is available for chainguard.dev/melange — see the affected versions and patch details below.
melange has Path Traversal When Resolving External Pipelines via Unvalidated pipeline[].uses
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-29050.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-29050 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
chainguard.dev/melangeReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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 /.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | chainguard.dev/melange | ≥ 0.32.0&&< 0.43.4 | 0.43.4go get chainguard.dev/melange@v0.43.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for chainguard.dev/melange, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update chainguard.dev/melange to 0.43.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-29050 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-29050 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-29050. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-29050 in your dependencies?
O3 Security finds CVE-2026-29050 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.