The vulnerability allows attackers who can influence a melange configuration file, such as in pull‑request‑driven continuous integration, to set the pipeline[].uses field to a value containing directory traversal or an absolute path. The build process interprets this value as a file name relative to the configured pipeline directory, which can be moved outside the intended directory using "../" sequences or an absolute path. The resulting file is parsed as a new pipeline definition and any commands listed in its runs block are executed via /bin/sh –c in the build sandbox, giving the attacker the ability to run arbitrary shell commands in the build environment. This flaw is a classic directory traversal (CWE‑22) that leads to remote code execution.

The flaw exists in Chainguard Dev's melange from version 0.32.0 through 0.43.3. The affected product is the melange command‑line tool, which builds Android application packages using declarative pipelines.

The CVSS score is 6.1, indicating moderate severity, and the EPSS score is <1%, suggesting a low probability of exploitation at the moment. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector is through construction of a malicious or tampered configuration file that is retrieved as part of a CI or build‑as‑a‑service workflow; once the configuration file is processed, the attacker can inject shell commands that run in the build sandbox.