Description
Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. This vulnerability is fixed in 1.152.1.
Published: 2026-05-28
Score: 6.8 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-8q93-326v-3m7g Synapse CPU starvation (Denial of Service)
History

Wed, 03 Jun 2026 02:30:00 +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': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Fri, 29 May 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Thu, 28 May 2026 20:00:00 +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, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. This vulnerability is fixed in 1.152.1.
Title Synapse CPU starvation (Denial of Service)
Weaknesses CWE-770
References
Metrics cvssV4_0

{'score': 6.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

Element Synapse
Element-hq Synapse
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-29T15:31:44.793Z

Reserved: 2026-05-08T18:45:10.097Z

Link: CVE-2026-45078

cve-icon Vulnrichment

Updated: 2026-05-29T15:31:41.450Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-28T17:16:31.750

Modified: 2026-06-03T02:15:33.060

Link: CVE-2026-45078

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-28T19:45:24Z

Weaknesses