CVE-2021-33571 is a high-severity (CVSS 7.5) Server-Side Request Forgery (SSRF) vulnerability in django. A fix is available for django — see the affected versions and patch details below.
Django Access Control Bypass possibly leading to SSRF, RFI, and LFI attacks
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-33571 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
django🐍django🐍djangoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | django | ≥ 2.2a1&&< 2.2.24 | 2.2.24pip install --upgrade 'django==2.2.24' |
| 🐍PyPI | django | ≥ 3.0a1&&< 3.1.12 | 3.1.12pip install --upgrade 'django==3.1.12' |
| 🐍PyPI | django | ≥ 3.2a1&&< 3.2.4 | 3.2.4pip install --upgrade 'django==3.2.4' |
Affected Products
djangodjangoprojectfedorafedoraprojectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for django, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update django to 2.2.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33571 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Red Hat Update Infrastructure is in maintenance phase and we will not be fixing Medium/Low impact security bugs. Reference: https://access.redhat.com/support/policy/updates/rhui In Red Hat OpenStack Platform 13, because the flaw has a lower impact and the fix would require a substantial amount of development, no…
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2021-33571 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 16.1 | python-django20-0:2.0.13-16.el8ost.1 | RHSA-2021:5070 |
| Red Hat OpenStack Platform 16.2 | python-django20-0:2.0.13-16.el8ost.1 | RHSA-2021:3490 |
| Red Hat Satellite 6.10 for RHEL 7 | python3-django-0:2.2.24-1.el7pc | RHSA-2021:4702 |
Frequently Asked Questions
Is CVE-2021-33571 in your dependencies?
Find it across PyPI, including transitive dependencies.