CVE-2026-42301

Workarounds

None

pyp2spec was writing PyPI package metadata (e.g. the summary field) into the generated spec file without escaping RPM macro directives. When a packager then runs rpmbuild, those directives get evaluated, so a malicious package can execute arbitrary commands on the build machine.

The macro evaluates during spec parsing, not only during the build step. Any rpm tool touching the generated spec triggers execution, rpmbuild -bs, rpmbuild --nobuild, rpm -q --specfile, so the victim doesn't need to commit to a full build before getting compromised. The realistic attack path is typosquatting or targeting a package known to be under Fedora review rather than drive-by publishing. Fedora packagers hold dist-git SSH keys, Koji build credentials, and Bodhi update credentials, so compromise of one packager's workstation enables committing malicious source to dist-git and riding it through the normal build pipeline to end users.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-42301 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 (0.14.1); upgrading removes the vulnerable code path.

Kodem intelligence

Patched in 0.14.1.

1. What is CVE-2026-42301? CVE-2026-42301 is a high-severity improper input validation vulnerability in pyp2spec (pip), affecting versions < 0.14.1. It is fixed in 0.14.1. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-42301? CVE-2026-42301 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.
3. Which versions of pyp2spec are affected by CVE-2026-42301? pyp2spec (pip) versions < 0.14.1 is affected.
4. Is there a fix for CVE-2026-42301? Yes. CVE-2026-42301 is fixed in 0.14.1. Upgrade to this version or later.
5. Is CVE-2026-42301 exploitable, and should I be worried? Whether CVE-2026-42301 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
6. What actually determines whether CVE-2026-42301 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.
7. How do I fix CVE-2026-42301? Upgrade pyp2spec to 0.14.1 or later.