CVE-2026-29051

Description

### Impact `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. ### Patches 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](https://github.com/chainguard-dev/melange/commit/84f3b450ce6e472c4abb8dc4c26d0ce8ac1259ac)). ### Workarounds 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. ### Credits melange thanks Oleh Konko ([@1seal](https://github.com/1seal) from [1seal.org](https://1seal.org/)) for discovering and reporting this issue.

How to fix CVE-2026-29051

To remediate CVE-2026-29051, upgrade the affected package to a fixed version below.

• —upgrade to 0.43.4 or later

Is CVE-2026-29051 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (1)