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.
History

Mon, 03 Nov 2025 22:30:00 +0000

Type Values Removed Values Added
References

cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published: 2021-05-06T00:00:00.000Z

Updated: 2025-11-03T21:44:43.122Z

Reserved: 2021-04-01T00:00:00.000Z

Link: CVE-2021-29921

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2021-05-06T13:15:12.573

Modified: 2025-11-03T22:15:48.057

Link: CVE-2021-29921

cve-icon Redhat

Severity : Moderate

Publid Date: 2021-04-30T00:00:00Z

Links: CVE-2021-29921 - Bugzilla