Bug 2558575 (CVE-2026-96639)

Summary:	CVE-2026-96639 pillow: Pillow multi-frame loaders can reuse stale native image storage after mode transitions
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	unspecified	CC:	alinfoot, anthomas, bbrownin, dschmidt, dtrifiro, ehelms, ggainey, jlanda, jpasqual, juwatts, kshier, mdellweg, mhulan, mwoodson, nmoumoul, osousa, pcreech, rbobbitt, rchan, rhel-process-autobot, simaishi, smallamp, stcannon, tmalecek, watson-tool-maintainers, weaton, yguenane
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Pillow. When processing multi-frame images that transition between different color modes, Pillow reuses an undersized native memory buffer without verifying that its format matches the subsequent frame. A remote attacker can exploit this flaw by providing a specially crafted multi-frame image file, causing an out-of-bounds memory write. Successful exploitation can lead to arbitrary code execution or a Denial of Service (DoS) resulting from an application crash.	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 2026-10-21 21:24:53 UTC

Pillow is a Python imaging library. From 11.0.0 until 13.0.0, multi-frame loaders can retain an ImagingCore allocation created for a narrow frame mode while a later frame of the same dimensions changes the logical mode and decoder tiles to wider RGB or CMYK data. ImageFile.load_prepare() reuses the stale native storage because _im is non-null without verifying that its mode and size still match. Crafted PSD, MPO, DCX, or MIC frame transitions can then write wider pixels into the narrow allocation, causing native out-of-bounds writes and crashes. The MPO path can also cause a native over-read and, in demonstrated runtime-specific profiles, command execution. This issue is fixed in version 13.0.0.