Summary
melange affected by potential host command execution via license-check YAML mode patch pipeline
Full technical description
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.
Fix: Fixed in bd132535 , Released in 0.40.3.
Acknowledgements
melange thanks Oleh Konko (@1seal) from 1seal for discovering and reporting this issue.
Impact
Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.
CVE-2026-25143 has a CVSS score of 7.8 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.40.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-25143? CVE-2026-25143 is a high-severity OS command injection vulnerability in chainguard.dev/melange (go), affecting versions >= 0.10.0, < 0.40.3. It is fixed in 0.40.3. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
- How severe is CVE-2026-25143? CVE-2026-25143 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of chainguard.dev/melange are affected by CVE-2026-25143? chainguard.dev/melange (go) versions >= 0.10.0, < 0.40.3 is affected.
- Is there a fix for CVE-2026-25143? Yes. CVE-2026-25143 is fixed in 0.40.3. Upgrade to this version or later.
- Is CVE-2026-25143 exploitable, and should I be worried? Whether CVE-2026-25143 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-25143 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-25143? Upgrade
chainguard.dev/melangeto 0.40.3 or later.