Bug 2545386 (CVE-2026-104874)

Summary:	CVE-2026-104874 multidict: multidict: Denial of Service via memory leak in items-view operations
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	alinfoot, anpicker, anthomas, aprice, bbrownin, bparees, brasmith, cahl, cochase, dfreiber, dranck, drow, dschmidt, dtrifiro, ebourniv, ehelms, gbenhaim, ggainey, gtanzill, hasun, ikhan, ilpinto, jburrell, jbuscemi, jdobes, jfula, jholecek, jlanda, jmitchel, jowilson, jpasqual, jsamir, juwatts, jwong, kaycoth, kshier, lbrazdil, ljawale, ltomasbo, mdellweg, mhulan, mminar, msilmser, niyer, nmoumoul, nyancey, oezr, omaciel, ometelka, orabin, osousa, pakotvan, pcreech, ptisnovs, rbiba, rbobbitt, rchan, rjohnson, sbunciak, simaishi, smallamp, sskracic, stcannon, sthirugn, syedriko, tmalecek, tpfromme, ttakamiy, twaugh, vkumar, weaton, xdharmai, yguenane, ykashtan, zzhou
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in multidict. The multidict C extension fails to release object references during certain items-view union and subtraction operations. An attacker could exploit this vulnerability by supplying crafted input sequences to applications performing these operations, triggering uncollectable memory leaks. This issue can cause unbounded process memory growth, ultimately leading to a Denial of Service (DoS).	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-02 20:31:22 UTC

Multidict is an implementation of a multidict data structure. From 6.7.0 until 6.9.1, the C extension's items-view reflected union operation, operand | d.items(), in multidict_itemsview_or2_impl and subtraction operation, d.items() - operand, in multidict_itemsview_sub1_impl fail to release new key-identity and value references returned for each operand element. Applications that perform these operations over attacker-influenced sequences can leak two strong references per element, and garbage collection cannot reclaim them, so repeated operations can cause unbounded process memory growth and denial of service. Forward union, intersection, non-tuple operand elements, and pure-Python builds are not affected by this reference leak. This issue is fixed in version 6.9.1.