Vulnerability Details CVE-2026-54283
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.003
EPSS Ranking 19.0%
CVSS Severity
CVSS v3 Score 7.5