CVE-2026-29050
Vulnérabilité moyenne dans melange (chainguard-dev)
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 `/`.
Gravité et risque d'exploitation
CVE-2026-29050 obtient un score CVSS de 6.1/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.18 %, ce qui la place devant 7.3 % des CVE référencées.
Que faire ?
- Vérifiez si melange (versions >= 0.32.0, < 0.43.4) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.