CVE-2026-45076

Synapse pagination denial of service

Published May 28, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-6qf2-7x63-mm6v Synapse pagination Denial of Service
History
Type Values Removed Values Added
First Time appeared Element
Element synapse
CPEs cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:*
Vendors & Products Element
Element synapse
Metrics cvssV3_1

{'score': 2.7, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Element-hq
Element-hq synapse
Vendors & Products Element-hq
Element-hq synapse
Type Values Removed Values Added
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.
Title Synapse pagination denial of service
Weaknesses CWE-20
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 2, 2026, 2:51 PM
Reserved
May 8, 2026, 6:45 PM
Status
Analyzed
Published
May 28, 2026, 5:16 PM
Modified
Oct 26, 2026, 1:10 PM