CVE-2026-25673: Potential denial-of-service vulnerability in URLField via Unicode normalization on Windows
Vulnerability summary
CVE-2026-25673 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in djangoproject django. EPSS estimates a 0.84% chance of exploitation in the next 30 days, higher than 57.9% of scored vulnerabilities.
Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 0 · Related 1Timeline
- 03-03-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
5 scores · 5 sources · 1 version- OSV · PypiEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVDNIST7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.84%
Chance of exploitation in the next 30 days
Percentile
58%
Versus all other CVEs
30-day change
Decrease -0.30 pp
From 1.14% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
- CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard3 products
- authentik-fips< 2026.2.1-r0
- awx< 24.6.1-r30
- label-studio< 1.22.0-r7
Alpine1 product
- py3-django< 4.2.29-r0
Djangoproject1 product
- django≥ 4.2, < 4.2.29 | ≥ 4.2.0, < 4.2.29 | ≥ 5.2, < 5.2.12 | ≥ 6.0, < 6.0.3
PyPI1 product
- django≥ 5.2, < 5.2.12 | ≥ 4.2, < 4.2.29 | ≥ 6.0, < 6.0.3
4 vendors · 6 products
References
16 links
- github.com/django/djangoPACKAGE
Show all 16 references
- pypi.org/project/djangoPACKAGE
- pypi.org/project/Django/PACKAGE