Bug 2330185 (CVE-2024-53863)

Summary:	CVE-2024-53863 matrix-synapse: Synapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decoders
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	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:	2330239, 2330240
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Description OSIDB Bzimport 2024-12-03 17:01:09 UTC

Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.