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CVE-2026-45076

Low

Description

Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.

SeverityLow
CVSS2.7
Exploit probability—
ProductElement Synapse
PublishedMay 28, 2026
First seenMay 28, 2026
Weakness typeCWE-20Improper input validation

How to fix

Update
  • element synapse1.152.1 or later
  • matrix-synapse1.152.1 or later

Affected products

ProductAffected versionsFixed in
element synapsev < 1.152.11.152.1
matrix-synapsePyPIv < 1.152.11.152.1

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