CVE-2021-29921
CRITICALCVSS 9.8/10EPSS 6.83%
Last modified
CVE-2021-29921 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 6.83% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Python | Python | >= 3.8.0, < 3.8.12 |
| Python | Python | >= 3.9.0, < 3.9.5 |
| Oracle | Communications Cloud Native Core Automated Test Suite | 1.8.0 |
| Oracle | Communications Cloud Native Core Binding Support Function | 1.11.0 |
| Oracle | Communications Cloud Native Core Network Slice Selection Function | 1.8.0 |
| Oracle | Graalvm | 20.3.2 |
| Oracle | Graalvm | 21.1.0 |
| Oracle | Zfs Storage Appliance Kit | 8.8 |
References
- https://bugs.python.org/issue36384Issue Tracking, Patch, Vendor Advisory
- https://docs.python.org/3/library/ipaddress.htmlVendor Advisory
- https://github.com/python/cpython/pull/12577Patch, Third Party Advisory
- https://github.com/python/cpython/pull/25099Patch, Third Party Advisory
- https://github.com/sickcodesThird Party Advisory
- https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-014.mdExploit, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210622-0003/Third Party Advisory
- https://sick.codes/sick-2021-014Exploit, Third Party Advisory
- https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
- https://bugs.python.org/issue36384Issue Tracking, Patch, Vendor Advisory
- https://docs.python.org/3/library/ipaddress.htmlVendor Advisory
- https://github.com/python/cpython/pull/12577Patch, Third Party Advisory
- https://github.com/python/cpython/pull/25099Patch, Third Party Advisory
- https://github.com/sickcodesThird Party Advisory
- https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-014.mdExploit, Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210622-0003/Third Party Advisory
- https://sick.codes/sick-2021-014Exploit, Third Party Advisory
- https://www.oracle.com//security-alerts/cpujul2021.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpuoct2021.htmlPatch, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-29921?
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.
How severe is CVE-2021-29921?
CVE-2021-29921 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 6.83% probability of exploitation in the next 30 days.
How do I fix CVE-2021-29921?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-29921?
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