---
cve: "CVE-2021-29921"
severity: "LOW"
cvss: 3.1
epss: "6.9%"
vendor: "n/a"
kev: false
exploited: false
published: "2021-05-06 13:15:12"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T04:04:24+02:00"
---

# CVE-2021-29921

> 3.1 LOW · 🧪 PoC

## Beschreibung

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.

## Patch verfügbar (OSV)

- 07119dd38c9a6e5da84ca8a0a46acdf8a3e60ecf (Commit)
- 0a7dcbdb13f1f2ab6e76e1cff47e80fb263f5da0 (Commit)

## Referenzen

- <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>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-29921) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_