CVE-2021-29921

Published: May 6, 2021

Modified: Nov 3, 2025

PUBLISHED

Description

In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the octets of an IP address string. This (in some situations) allows attackers to bypass access control that is based on IP addresses.

Vendor	Product	Versions
n/a	n/a	affected `n/a`

References

https://github.com/sickcodes

https://docs.python.org/3/library/ipaddress.html

https://github.com/python/cpython/blob/63298930fb531ba2bb4f23bc3b915dbf1e17e9e1/Misc/NEWS.d/3.8.0a4.rst

https://sick.codes/sick-2021-014

https://www.oracle.com//security-alerts/cpujul2021.html

https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-014.md

https://python-security.readthedocs.io/vuln/ipaddress-ipv4-leading-zeros.html

https://bugs.python.org/issue36384

https://github.com/python/cpython/pull/12577

https://github.com/python/cpython/pull/25099

https://security.netapp.com/advisory/ntap-20210622-0003/

https://www.oracle.com/security-alerts/cpuoct2021.html

https://www.oracle.com/security-alerts/cpujan2022.html

https://www.oracle.com/security-alerts/cpuapr2022.html

https://www.oracle.com/security-alerts/cpujul2022.html

GLSA-202305-02

vendor-advisory

Security Training

Train your team to recognize and prevent security threats with our comprehensive security awareness program.

Start Training

Vulnerability Scanning

Discover vulnerabilities in your applications and infrastructure before attackers do.

Scan Now

CVE-2021-29921

Description

Affected Products

References