CVE-2026-29051 is a medium-severity (CVSS 4.4) 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 via .PKGINFO in --persist-lint-results
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-2026-29051.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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, melange lint --persist-lint-results (opt-in flag, also usable via melange build --persist-lint-results) constructs output file paths by joining --out-dir with the arch and pkgname values read from the .PKGINFO control file of the APK being linted. In affected versions these values were not validated for path separators or .. sequences, so an attacker who can supply an APK to a melange-based lint/build pipeline (e.g. CI that lints third-party APKs, or build-as-a-service) could cause melange to write lint-<pkgname>-<pkgver>-r<epoch>.json to an arbitrary .json path reachable by the melange process. The written file is a JSON lint report whose content is partially attacker-influenced. There is no direct code-execution path, but the write can clobber other JSON artifacts on the filesystem. The issue only affects deployments that explicitly pass --persist-lint-results; the flag is off by default. The issue is fixed in melange v0.43.4 by validating arch and pkgname for .., /, and filepath.Separator before path construction in pkg/linter/results.go (commit 84f3b45). As a workaround, do not pass --persist-lint-results when linting or building APKs whose .PKGINFO contents are not fully trusted. Running melange as a low-privileged user and confining writes to an isolated directory also limits impact.
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 |
Affected Products
melangechainguardDetection & 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-2026-29051 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2026-29051 in your dependencies?
Find it across Go, including transitive dependencies.