CVE-2021-45115 is a high-severity (CVSS 7.5) vulnerability in django. A fix is available for django — see the affected versions and patch details below.
Denial-of-service in Django
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-45115 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 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
An issue was discovered in Django 2.2 before 2.2.26, 3.2 before 3.2.11, and 4.0 before 4.0.1. UserAttributeSimilarityValidator incurred significant overhead in evaluating a submitted password that was artificially large in relation to the comparison values. In a situation where access to user registration was unrestricted, this provided a potential vector for a denial-of-service attack.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | django | ≥ 2.2a1&&< 2.2.26 | 2.2.26pip install --upgrade 'django==2.2.26' |
| 🐍PyPI | django | ≥ 3.2a1&&< 3.2.11 | 3.2.11pip install --upgrade 'django==3.2.11' |
| 🐍PyPI | django | ≥ 4.0a1&&< 4.0.1 | 4.0.1pip install --upgrade 'django==4.0.1' |
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 2.2.26 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-45115 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
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.
In Red Hat OpenStack Platform, because the flaw's impact is lower and the impacted functionality is not directly used, no update will be provided at this time for the python-django20 package.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Satellite 6.11 for RHEL 8 | python-django-0:3.2.13-1.el8pc | RHSA-2022:5498 |
Frequently Asked Questions
Is CVE-2021-45115 in your dependencies?
Find it across PyPI, including transitive dependencies.