Bug 2532473 (CVE-2026-45057)

Summary:	CVE-2026-45057 matrix-sdk-ui: matrix-sdk-ui: Message Spoofing via Incomplete Edit Validation
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	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in matrix-sdk-ui. The component's message edit validation logic does not properly enforce encryption for replacement events, even when the original message was encrypted. This vulnerability allows a malicious homeserver administrator, or an attacker with similar capabilities, to impersonate users by spoofing messages as if they were sent by a victim.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Bug Depends On:	2532943
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Description OSIDB Bzimport 2026-09-11 23:22:17 UTC

matrix-sdk-ui provides GUI-centric utilities on top of matrix-rust-sdk. The message edit validation logic in the  `matrix-sdk-ui` crate prior to 0.17.0 is missing a check: when replacing an encrypted event, the replacement event itself is not required to be encrypted. This enables a malicious homeserver administrators (or actors with equivalent power) to impersonate or spoof messages as if they were sent by a victim user. `matrix-sdk-ui` 0.17.0 fixes the message edit validation logic to align with the algorithm for replacement events[^1] described in the Matrix specification. No known workarounds are available.