CVE-2026-25673
Published: 03 March 2026
Summary
CVE-2026-25673 is a high-severity Uncontrolled Resource Consumption (CWE-400) vulnerability in Djangoproject Django. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 47.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limiting concurrent sessions directly prevents uncontrolled resource consumption by capping the number of active sessions per user or account.
Contingency plan testing includes resource exhaustion scenarios to verify recovery, making it harder for attackers to sustain exploits that cause uncontrolled consumption.
Updated contingency plans include current procedures to detect, contain, and recover from resource exhaustion, limiting an attacker's ability to sustain impact from uncontrolled consumption.
Alternate site allows resumption of operations if resource exhaustion at the primary site is exploited to cause unavailability.
Alternate telecommunications services enable resumption of essential functions when primary services become unavailable due to uncontrolled resource consumption.
Planning and coordination of security activities (scans, tests, maintenance) directly imposes scheduling and throttling that prevents those activities from producing uncontrolled resource consumption.
Performance metrics and monitoring inherently track resource consumption patterns, making uncontrolled consumption easier to detect and mitigate.
Terminating idle connections bounds resource consumption that would otherwise allow uncontrolled accumulation of open sessions.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated exploitation of Django URLField causes application-level resource exhaustion/DoS on crafted Unicode input, directly enabling T1499.004 (Application or System Exploitation).
NVD 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…
more
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.
Deeper analysisAI
CVE-2026-25673 is a denial-of-service vulnerability in the Django web framework, specifically affecting the `URLField.to_python()` method. This method invokes `urllib.parse.urlsplit()`, which on Windows systems performs NFKC normalization that becomes disproportionately slow when processing large URL inputs containing certain Unicode characters. The issue impacts Django versions 6.0 before 6.0.3, 5.2 before 5.2.12, and 4.2 before 4.2.29; earlier unsupported series such as 5.0.x, 4.1.x, and 3.2.x were not evaluated but may also be vulnerable.
A remote, unauthenticated attacker can exploit this vulnerability by submitting large URL inputs with the problematic Unicode characters to any Django application that processes URLs via `URLField`. The resulting computational overload leads to significant performance degradation or complete denial of service, with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) reflecting its network accessibility, low complexity, and high availability impact. The associated CWEs are CWE-400 (Uncontrolled Resource Consumption) and CWE-770 (Allocation of Resources Without Limits or Throttling).
Django's security advisories, detailed in their release notes, announcement group, and weblog, recommend upgrading to the fixed versions—6.0.3, 5.2.12, or 4.2.29—to mitigate the issue. The vulnerability was reported by Seokchan Yoon.
Details
- CWE(s)