# CVE-2026-25673: Django denial of service in URLField via Unicode normalization on Windows

Source: https://junglewise.ai/threats/cve-2026-25673-django-denial-of-service-in-urlfield-via-unicode-normalization-on  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-03. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-25673 · Severity: high · CVSS 7.5 · Published 2026-03-03

A vulnerability in the Django web framework can allow an attacker to crash or slow down a website running on Windows. By submitting specially crafted, large web addresses (URLs) containing specific Unicode characters, an attacker can trigger an extremely slow processing task that consumes server resources. This results in a denial of service, making the application unavailable to legitimate users.

Technologies: [Django (PyPI)](https://junglewise.ai/threats/technologies/django). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-25673 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-25673 being exploited in the wild.

**How severe is CVE-2026-25673?** High severity, with a CVSS score of 7.5, published 3 March 2026.

**Which products and versions are affected?** Django (PyPI) ECOSYSTEM:introduced=4.2,fixed=4.2.29,introduced=5.2,fixed=5.2.12,introduced=6.0,fixed=6.0.3, ECOSYSTEM:introduced=6.0,fixed=6.0.3.

**Is there a fix for CVE-2026-25673?** Yes. Django (PyPI): upgrade to 6.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-25673 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-25673?** Check whether you run Django (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Django (PyPI): upgrade to 6.0.3 or later

  ```sh
  pip install "Django>=6.0.3"
  ```


## Technical details

A denial of service (DoS) vulnerability exists in Django's `URLField.to_python()` method when running on Windows. The component calls `urllib.parse.urlsplit()`, which performs NFKC normalization. On Windows, this process is disproportionately slow when handling certain Unicode characters. A remote, unauthenticated attacker can exploit this by submitting large URL inputs containing these specific characters, leading to uncontrolled resource consumption and service exhaustion. The issue is fixed in Django versions 6.0.3, 5.2.12, and 4.2.29.

## Affected products

- Django Software Foundation Django 6.0 before 6.0.3, 5.2 before 5.2.12, 4.2 before 4.2.29

## Identifiers

- CVE-2026-25673
- GHSA-8p8v-wh79-9r56
- PYSEC-2026-2448

## Timeline

- 2026-03-03: disclosed
- 2026-03-03: patched
- 2026-03-03: advisory

## References

- [https://pypi.org/project/Django/](https://pypi.org/project/Django/)
- [https://docs.djangoproject.com/en/dev/releases/security/](https://docs.djangoproject.com/en/dev/releases/security/)
- [https://groups.google.com/g/django-announce](https://groups.google.com/g/django-announce)
- [https://www.djangoproject.com/weblog/2026/mar/03/security-releases/](https://www.djangoproject.com/weblog/2026/mar/03/security-releases/)
- [https://access.redhat.com/security/cve/CVE-2026-25673](https://access.redhat.com/security/cve/CVE-2026-25673)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2444115](https://bugzilla.redhat.com/show_bug.cgi?id=2444115)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25673.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-25673.json)

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