The vulnerability is an input-handling flaw in melange’s patch pipeline, where values supplied through patch-related inputs are incorporated into shell scripts without proper quoting or validation. This flaw permits an attacker to inject shell metacharacters and run arbitrary commands with the privileges of the melange build process, compromising confidentiality, integrity, and availability of the build host. It is classified as CWE‑78: OS Command Injection.

The issue affects Chainguard’s melange version 0.10.0 up to, but not including, 0.40.3. Any deployment of these versions that uses the default patch pipeline – invoked through melange build or melange license‑check operations – is vulnerable. Versions 0.40.3 and newer contain the patch.

The CVSS score of 7.8 indicates a high‑severity vulnerability. The EPSS score of less than 1 % suggests that exploitation is currently low probability, and the vulnerability is not listed in CISA’s KEV catalog. However, the flaw can be leveraged through the patch pipeline by an attacker who can influence inputs, such as through pull‑request driven continuous integration, build‑as‑a‑service setups, or untrusted configuration values. The attack can be performed without requiring additional credentials, relying solely on the ability to tamper with patch‑related inputs.