Bug 2532413 (CVE-2026-45056)

Summary:	CVE-2026-45056 matrix-sdk-crypto: matrix-sdk-crypto: Forged encrypted events via missing user ID check
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-crypto. This component, responsible for handling end-to-end encryption in Matrix clients, was missing a user ID check during the decryption of Olm-encrypted events that contained the `sender_device_keys` property. An attacker, in collusion with the homeserver operator, could exploit this vulnerability to forge an encrypted to-device event. This could lead to unauthorized message creation and potential integrity issues within the Matrix communication.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 22:52:42 UTC

matrix-sdk-crypto is a no-network-IO implementation of a state machine that handles end-to-end encryption for Matrix clients. Starting in version 0.12.0 and prior to version 0.17.0, the matrix-sdk-crypto crate was missing a check for the user ID when decrypting an Olm-encrypted event containing the `sender_device_keys` property. This could be exploited to forge an encrypted to-device event, but only if the attacker colludes with the homeserver operator. This issue is fixed in matrix-sdk-crypto 0.17.0. There are no known workarounds for the issue.