What’s Vulnerable › Vulnerabilities
CVE-2026-54283: Starlette: request.form() limits silently ignored for application/x-www-form-urlencoded enable DoS
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.5% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-06-22 · updated 2026-10-25
- Weakness: CWE-770
Description
Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.
Affected products
- Kludex starlette: from 0.4.1 before 1.3.1 — fixed in 1.3.1
How to fix
Upgrade to a fixed version: Kludex starlette 1.3.1. Check the vendor advisory for mitigations.
References
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