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.