Bug 2491440 (CVE-2026-54283)

Summary:	CVE-2026-54283 starlette: Starlette: request.form() limits silently ignored for application/x-www-form-urlencoded enable DoS
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	alinfoot, anpicker, anthomas, aprice, bbrownin, dfreiber, dkeler, drow, dschmidt, dtrifiro, ehelms, fdeutsch, ggainey, hasun, ilpinto, jburrell, jdobes, jfula, jkoehler, jlanda, jowilson, jpasqual, jsamir, juwatts, jwong, kaycoth, kshier, lphiri, ltomasbo, mbarnett, mhayden, mhulan, nmoumoul, nyancey, oezr, omaciel, ometelka, orabin, oramraz, osousa, pcreech, prwatson, ptisnovs, rbryant, rchan, rjohnson, sdoran, simaishi, smallamp, smullick, stcannon, stirabos, suppawar, syedriko, teagle, thason, tmalecek, ttakamiy, vkumar, weaton, xdharmai, yguenane, ykashtan
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Starlette where the request.form() method silently ignores configured resource limits (max_fields and max_part_size) when parsing application/x-www-form-urlencoded data. An unauthenticated attacker can exploit this by sending a urlencoded request body with an arbitrarily large number of fields or an oversized field, causing denial of service through resource exhaustion.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-06-22 18:01:28 UTC

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.