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

published 2026-05-04 6 mo ago modified 2026-07-24 3 mo ago also GHSA-r35x-v8p8-xvhw , PYSEC-2026-3003 , EUVD-2026-28896

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits: 0; none known

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.

Patch / fix

fixed in 1 links 1

pypi pyp2spec 0.14.1

github.com/befeleme/pyp2spec/releases/tag/v0.14.1 release

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42301 updated 2026-09-18 cvss 7.3

pyp2spec: pyp2spec: Arbitrary command execution via unescaped RPM macro directives

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 5 mo ago (2026-05-11)

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
GitHub	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
OSV	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
pypi	pyp2spec	<0.14.1	0.14.1

Affected products

befeleme pyp2spec

Classification

Weakness

CWE-20 Improper Input Validation
CWE-94 Improper Control of Generation of Code

References

github.com /befeleme/pyp2spec/security/advisories/GHSA-r35x-v8p8-xvhw
web
github.com /befeleme/pyp2spec/releases/tag/v0.14.1
web
nvd.nist.gov /vuln/detail/CVE-2026-42301
advisory
github.com /befeleme/pyp2spec
package
pypi.org /project/pyp2spec
package
github.com /advisories/GHSA-r35x-v8p8-xvhw
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary