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.
Published: 2026-05-28
Score: 5.1 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-6qf2-7x63-mm6v Synapse pagination Denial of Service
History

Thu, 04 Jun 2026 18:15:00 +0000

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'}


Tue, 02 Jun 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Thu, 28 May 2026 19:00:00 +0000

Type Values Removed Values Added
First Time appeared Element-hq
Element-hq synapse
Vendors & Products Element-hq
Element-hq synapse

Thu, 28 May 2026 17:00:00 +0000

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'}


Subscriptions

Element Synapse
Element-hq Synapse
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-02T14:51:34.553Z

Reserved: 2026-05-08T18:45:10.096Z

Link: CVE-2026-45076

cve-icon Vulnrichment

Updated: 2026-06-02T14:51:26.936Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-28T17:16:31.590

Modified: 2026-06-04T18:04:26.643

Link: CVE-2026-45076

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-28T19:00:16Z

Weaknesses