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CVE-2026-42301

Improper Input Validation leading to Improper Control of Generation of Code ('Code Injection') in pyp2spec

7.8 HighFix available

pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, 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. This issue has been patched in version 0.14.1.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.20%Up 0.2 points since May 9, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.8

Improper Input Validation leading to Improper Control of Generation of Code ('Code Injection') in pyp2spec

pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, 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. This issue has been patched in version 0.14.1.

Record
CVE-2026-42301
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-94
Updated
2026-11-02
EUVDEUVD-2026-28896 7.8

pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, 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. This issue has been patched in version 0.14.1.

Record
EUVD-2026-28896
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-r35x-v8p8-xvhw 7.8

pyp2spec is Vulnerable to Code Injection

Impact

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.

Patches

Patched in 0.14.1.

Workarounds

None

Record
GHSA-r35x-v8p8-xvhw
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-94
Updated
2026-11-02
NVD 7.8

pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, 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. This issue has been patched in version 0.14.1.

Record
CVE-2026-42301
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-94
Updated
2026-11-02
OSV 7.8

Improper Input Validation leading to Improper Control of Generation of Code ('Code Injection') in pyp2spec

pyp2spec generates working Fedora RPM spec file for Python projects. Prior to version 0.14.1, 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. This issue has been patched in version 0.14.1.

Record
CVE-2026-42301
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-94
Updated
2026-11-02
OSVGHSA-r35x-v8p8-xvhw 7.8

pyp2spec is Vulnerable to Code Injection

Impact

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.

Patches

Patched in 0.14.1.

Workarounds

None

Record
GHSA-r35x-v8p8-xvhw
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness
CWE-20, CWE-94
Updated
2026-11-02
OSVPYSEC-2026-3003 7.8

pyp2spec is Vulnerable to Code Injection

Impact

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.

Patches

Patched in 0.14.1.

Workarounds

None

Record
PYSEC-2026-3003
CVSS 3.1
7.8 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
pyp2spec
PyPI
before 0.14.1
0.14.1
pyp2spec
PyPI
before 0.14.1, plus listed versions
0.1.00.10.00.11.00.11.10.12.0
Show 16 moreShow less
0.12.10.12.20.13.00.2.00.3.00.3.10.3.20.3.30.4.00.5.00.5.0a10.6.00.6.10.7.00.8.00.9.0
0.14.1

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-42301 is a high vulnerability (CVSS 7.8) in Befeleme Pyp2spec, published May 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.20%, the 9th percentile. Fixed in pyp2spec 0.14.1.

References

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