Medium 6.8Published May 28, 2026

CVE-2026-45078Synapse CPU starvation (Denial of Service)

Updated under an hour ago (Oct 27, 2026, 1:30 PM ET)

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It affects element-hq synapse and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for element-hq synapse

Exploited in the last 30 days

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.

CVSS: 6.8 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-770
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 29, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

element-hq synapse element_hq:synapse (from the name)	before 1.152.1	CNA record
element synapse element:synapse	before 1.152.1	NVD

References

References

https://github.com/element-hq/synapse/security/advisories/GHSA-8q93-326v-3m7g	x-refsource-confirm, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.