Bug 2491443 (CVE-2026-53540)

Summary:	CVE-2026-53540 python-multipart: Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	alinfoot, anpicker, anthomas, aprice, bbrownin, bparees, dfreiber, 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, 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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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:	2495855
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Description OSIDB Bzimport 2026-06-22 18:01:40 UTC

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parse_form() did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turned the bounded read into a read-until-EOF, so the entire body was loaded into memory in a single read instead of in fixed-size chunks. This vulnerability is fixed in 0.0.31.