CVE-2020-29651: py vulnerable to Regular Expression Denial of Service

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-12-09 · updated 2026-06-17

Description

A denial of service via regular expression in the py.path.svnwc component of py (aka python-py) through 1.9.0 could be used by attackers to cause a compute-time denial of service attack by supplying malicious input to the blame functionality.

Affected products

Fedoraproject Fedora: 32, 33
Oracle Corporation Oracle ZFS Storage Appliance Kit: 8.8
pytest Py: through 1.9.0
Pypi Py: before 1.10.0; 0.8.0-alpha2, 0.9.0, 0.9.1, 0.9.2, 1.0.0, 1.0.1 (+57) — fixed in 1.10.0

How to fix

Upgrade to a fixed version: Pypi Py 1.10.0. Check the vendor advisory for mitigations.

References

https://github.com/pytest-dev/py/issues/256
https://github.com/pytest-dev/py/pull/257
https://github.com/pytest-dev/py/pull/257/commits/4a9017dc6199d2a564b6e4b0aa39d6d8870e4144
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AYWNYEV3FGDHPIHX4DDUDMFZ6NLCQRC4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CHDTINIBJZ67T3W74QTBIY5LPKAXEOGR/
https://www.oracle.com/security-alerts/cpujul2022.html
https://github.com/pytest-dev/py/issues/256
https://github.com/pytest-dev/py/pull/257
https://github.com/pytest-dev/py/pull/257/commits/4a9017dc6199d2a564b6e4b0aa39d6d8870e4144
https://lists.debian.org/debian-lts-announce/2024/11/msg00024.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AYWNYEV3FGDHPIHX4DDUDMFZ6NLCQRC4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CHDTINIBJZ67T3W74QTBIY5LPKAXEOGR/

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