CVE-2021-29921
9.8
CRITICAL · CVSS 3.1 · EPSS 6.9% (pctl 94)
In your normal cycle
Critical by CVSS (9.8), but no sign of active exploitation.
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.
Scoring
| CVSS | 9.8 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| EPSS | 6.88% — more likely to be exploited than 94% of all CVEs |
| On CISA KEV | no |
| Public exploit | none known |
| Published | 2021-05-06 |
| Last modified | 2026-06-17 |
Affected (6)
| Vendor | Product |
|---|---|
| oracle | communications cloud native core automated test suite |
| oracle | communications cloud native core binding support function |
| oracle | communications cloud native core network slice selection function |
| oracle | graalvm |
| oracle | zfs storage appliance kit |
| python | python |
References
- https://bugs.python.org/issue36384
- https://docs.python.org/3/library/ipaddress.html
- https://github.com/python/cpython/blob/63298930fb531ba2bb4f23bc3b915dbf1e17e9e1/Misc/NEWS.d/3.8.0a4.rst
- https://github.com/python/cpython/pull/12577
- https://github.com/python/cpython/pull/25099
- https://github.com/sickcodes
- https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-014.md
- https://python-security.readthedocs.io/vuln/ipaddress-ipv4-leading-zeros.html
- https://security.gentoo.org/glsa/202305-02
- https://security.netapp.com/advisory/ntap-20210622-0003/
- https://sick.codes/sick-2021-014
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://bugs.python.org/issue36384
- https://docs.python.org/3/library/ipaddress.html
- https://github.com/python/cpython/blob/63298930fb531ba2bb4f23bc3b915dbf1e17e9e1/Misc/NEWS.d/3.8.0a4.rst
- https://github.com/python/cpython/pull/12577
→ the Explorer · watch your stack · NVD