What’s Vulnerable › Vulnerabilities

CVE-2021-33571: Django Access Control Bypass possibly leading to SSRF, RFI, and LFI attacks

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-08 · updated 2026-06-17
• Weakness: CWE-918

Description

In Django 2.2 before 2.2.24, 3.x before 3.1.12, and 3.2 before 3.2.4, URLValidator, validate_ipv4_address, and validate_ipv46_address do not prohibit leading zero characters in octal literals. This may allow a bypass of access control that is based on IP addresses. (validate_ipv4_address and validate_ipv46_address are unaffected with Python 3.9.5+..) .

Affected products

• Django: from 2.2 before 2.2.24; from 3.0 before 3.1.12; from 3.2 before 3.2.4 — fixed in 2.2.24, 3.1.12, 3.2.4
• Fedoraproject Fedora: 35
• Pypi Django: from 2.2 before 2.2.24; from 3.0 before 3.1.12; from 3.2 before 3.2.4; 2.2, 2.2.1, 2.2.10, 2.2.11, 2.2.12, 2.2.13 (+52) — fixed in 2.2.24, 3.1.12, 3.2.4

How to fix

Upgrade to a fixed version: Django 2.2.24, 3.1.12, 3.2.4; Pypi Django 2.2.24, 3.1.12, 3.2.4. Check the vendor advisory for mitigations.

References

• https://docs.djangoproject.com/en/3.2/releases/security/
• https://github.com/django/django/commit/203d4ab9ebcd72fc4d6eb7398e66ed9e474e118e
• https://github.com/django/django/commit/9f75e2e562fa0c0482f3dde6fc7399a9070b4a3d
• https://github.com/django/django/commit/f27c38ab5d90f68c9dd60cabef248a570c0be8fc
• https://groups.google.com/g/django-announce/c/sPyjSKMi8Eo
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/B4SQG2EAF4WCI2SLRL6XRDJ3RPK3ZRDV/
• https://security.netapp.com/advisory/ntap-20210727-0004/
• https://www.djangoproject.com/weblog/2021/jun/02/security-releases/
• https://docs.djangoproject.com/en/3.2/releases/security/
• https://github.com/django/django/commit/203d4ab9ebcd72fc4d6eb7398e66ed9e474e118e
• https://github.com/django/django/commit/9f75e2e562fa0c0482f3dde6fc7399a9070b4a3d
• https://github.com/django/django/commit/f27c38ab5d90f68c9dd60cabef248a570c0be8fc

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