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.

melange allows users to build apk packages using declarative pipelines. In version 0.40.5 and prior, melange update-cache downloads URIs from build configs via io.Copy without any size limit or HTTP client timeout (pkg/renovate/cache/cache.go). An attacker-controlled URI in a melange config can cause unbounded disk writes, exhausting disk on the build runne. There is no known patch publicly available.

melange allows users to build apk packages using declarative pipelines. From version 0.10.0 to before 0.40.3, an attacker who can influence inputs to the patch pipeline could execute arbitrary shell commands on the build host. The patch pipeline in pkg/build/pipelines/patch.yaml embeds input-derived values (series paths, patch filenames, and numeric parameters) into shell scripts without proper quoting or validation, allowing shell metacharacters to break out of their intended context. The vulnerability affects the built-in patch pipeline which can be invoked through melange build and melange license-check operations. An attacker who can control patch-related inputs (e.g., through pull request-driven CI, build-as-a-service, or by influencing melange configurations) can inject shell metacharacters such as backticks, command substitutions $(…), semicolons, pipes, or redirections to execute arbitrary commands with the privileges of the melange build process. This issue has been patched in version 0.40.3.

melange allows users to build apk packages using declarative pipelines. From version 0.3.0 to before 0.40.3, an attacker who can provide build input values, but not modify pipeline definitions, could execute arbitrary shell commands if the pipeline uses ${{vars.*}} or ${{inputs.*}} substitutions in working-directory. The field is embedded into shell scripts without proper quote escaping. This issue has been patched in version 0.40.3.

melange allows users to build apk packages using declarative pipelines. From version 0.14.0 to before 0.40.3, an attacker who can influence a melange configuration file (e.g., through pull request-driven CI or build-as-a-service scenarios) could read arbitrary files from the host system. The LicensingInfos function in pkg/config/config.go reads license files specified in copyright[].license-path without validating that paths remain within the workspace directory, allowing path traversal via ../ sequences. The contents of the traversed file are embedded into the generated SBOM as license text, enabling exfiltration of sensitive data through build artifacts. This issue has been patched in version 0.40.3.

melange allows users to build apk packages using declarative pipelines. In version 0.11.3 to before 0.40.3, an attacker who can influence the tar stream from a QEMU guest VM could write files outside the intended workspace directory on the host. The retrieveWorkspace function extracts tar entries without validating that paths stay within the workspace, allowing path traversal via ../ sequences. This issue has been patched in version 0.40.3.