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TI-2021-10543 Aliases CVE-2021-29921GHSA-cxqv-r2cc-r9c9

In Python before 3,9,5, the ipaddress library mishandles leading zero characters in the…

Priority MEDIUM 58Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.06761 94th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed Red Hat: 3 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*3.8.0 to before 3.8.12; 3.9.0 to before 3.9.5Vulnerablepython-pillow
cpe:2.3:a:oracle:communications_cloud_native_core_automated_test_suite:1.8.0:*:*:*:*:*:*:*1.8.0VulnerableOracle
cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:1.11.0:*:*:*:*:*:*:*1.11.0VulnerableOracle
cpe:2.3:a:oracle:communications_cloud_native_core_network_slice_selection_function:1.8.0:*:*:*:*:*:*:*1.8.0VulnerableOracle
cpe:2.3:a:oracle:graalvm:20.3.2:*:*:*:enterprise:*:*:*20.3.2VulnerableOracle
cpe:2.3:a:oracle:graalvm:21.1.0:*:*:*:enterprise:*:*:*21.1.0VulnerableOracle
cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*8.8VulnerableOracle
  • cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions 3.8.0 to before 3.8.12; 3.9.0 to before 3.9.5 Vulnerable ·python-pillow
  • cpe:2.3:a:oracle:communications_cloud_native_core_automated_test_suite:1.8.0:*:*:*:*:*:*:* Versions 1.8.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:communications_cloud_native_core_binding_support_function:1.11.0:*:*:*:*:*:*:* Versions 1.11.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:communications_cloud_native_core_network_slice_selection_function:1.8.0:*:*:*:*:*:*:* Versions 1.8.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:graalvm:20.3.2:*:*:*:enterprise:*:*:* Versions 20.3.2 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:graalvm:21.1.0:*:*:*:enterprise:*:*:* Versions 21.1.0 Vulnerable ·Oracle
  • cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* Versions 8.8 Vulnerable ·Oracle

Remediation

Red Hat 3 advisories

  • RHSA-2021:4160 Released 2021-11-09 · Red Hat rating Moderate
    python39:3.9 and python39-devel:3.9 security update
    • Red Hat CodeReady Linux Builder (v. 8) Cython-0.29.21-5.module+el8.4.0+9822+20bf1249.src::python39-devel:3.9, pybind11-2.6.1-2.module+el8.4.0+9822+20bf1249.src::python39-devel:3.9, pytest-6.0.2-2.module+el8.4.0+9822+20bf1249.src::python39-devel:3.9 +33
    • Red Hat Enterprise Linux AppStream (v. 8) PyYAML-5.4.1-1.module+el8.5.0+10613+59a13ec4.src::python39:3.9, mod_wsgi-4.7.1-4.module+el8.4.0+9822+20bf1249.src::python39:3.9, numpy-1.19.4-3.module+el8.5.0+12204+54860423.src::python39:3.9 +47
  • RHSA-2021:4162 Released 2021-11-09 · Red Hat rating Moderate
    python38:3.8 and python38-devel:3.8 security update
    • Red Hat CodeReady Linux Builder (v. 8) pytest-4.6.6-3.module+el8.4.0+8888+89bc7e79.src::python38-devel:3.8, python-atomicwrites-1.3.0-8.module+el8.4.0+8888+89bc7e79.src::python38-devel:3.8, python-attrs-19.3.0-3.module+el8.4.0+8888+89bc7e79.src::python38-devel:3.8 +15
    • Red Hat Enterprise Linux AppStream (v. 8) Cython-0.29.14-4.module+el8.4.0+8888+89bc7e79.src::python38:3.8, PyYAML-5.4.1-1.module+el8.5.0+10721+14d8e0d5.src::python38:3.8, babel-2.7.0-11.module+el8.5.0+11015+9c1c7c42.src::python38:3.8 +47
  • RHSA-2021:3254 Released 2021-08-24 · Red Hat rating Moderate
    rh-python38 security, bug fix, and enhancement update
    • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
    • Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14
    • Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) rh-python38-babel-2.7.0-12.el7, rh-python38-python-3.8.11-2.el7, rh-python38-python-babel-2.7.0-12.el7 +14

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat CodeReady Linux Builder (v. 8)Fixed RHSA-2021:4160, RHSA-2021:4162
Red Hat Enterprise Linux AppStream (v. 8)Fixed RHSA-2021:4160, RHSA-2021:4162
Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7)Fixed RHSA-2021:3254
Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7)Fixed RHSA-2021:3254
Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7)Fixed RHSA-2021:3254
Not affected: 3 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Software Collections

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-29921
  2. 2026-10-03 Alias added: GHSA-cxqv-r2cc-r9c9
  3. 2026-10-08 CISA SSVC decision points changed

References

Exploit 2

Patch 7

Advisory 6

Other 1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences