CVE-2026-25673 Potential denial-of-service vulnerability in URLField via Unicode normalization on Windows
Remote attackers can cause denial of service in Django applications on Windows by sending large URL inputs with specific Unicode characters.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-25673?
CVE-2026-25673 is a high-severity denial of service vulnerability in Djangoproject Django, published on 3 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An issue was discovered in 6.0 before 6.0.3, 5.2 before 5.2.12, and 4.2 before 4.2.29. `URLField.to_python()` in Django calls `urllib.parse.urlsplit()`, which performs NFKC normalization on Windows that is disproportionately slow for certain Unicode characters, allowing a remote attacker to cause denial of service via large URL inputs containing these characters. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Seokchan Yoon for reporting this issue.
Which versions are affected by CVE-2026-25673?
8 open source packages ship an affected version, including django and Django. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
django Bitnami | From 4.2.0 | 4.2.29, 5.2.12, 6.0.3 |
django PyPI | From 4.2 | 4.2.29, 5.2.12, 6.0.3 |
django PyPI | From 4.2 | 4.2.29 |
django PyPI | From 5.2 | 5.2.12 |
django PyPI | From 6.0 | 6.0.3 |
Django PyPI | From 4.2 | 4.2.29 |
2 more packages
Django PyPI | From 5.2 | 5.2.12 |
Django PyPI | From 6.0 | 6.0.3 |
Products include Djangoproject Django.
How do I fix CVE-2026-25673?
Upgrade django to a fixed version for your release line: 4.2.29, 5.2.12 or 6.0.3.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-25673 being exploited?
There is no known exploitation of CVE-2026-25673 in the wild and no public exploit code.
Other vulnerabilities in Djangoproject Django
- CVE-2026-4277 Privilege abuse in GenericInlineModelAdmin
- CVE-2024-53908 Django SQL injection in HasKey(lhs, rhs) on Oracle
- CVE-2024-42005 Django SQL injection vulnerability
- CVE-2023-31047 Django bypasses validation when using one form field to upload multiple files
- CVE-2022-34265 Django `Trunc()` and `Extract()` database functions vulnerable to SQL Injection
Sources
Also known as BIT-django-2026-25673, ECHO-de02-7575-4370, GHSA-8p8v-wh79-9r56, MINI-3fmj-7xpr-rqx5, PYSEC-2026-2448.