What is CVE-2026-45078?

CVE-2026-45078 is a medium-severity vulnerability in Element Synapse, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.5/10. Published 2026-05-28.

How severe is CVE-2026-45078?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Resource exhaustion in Element Synapse

CVE-2026-45078

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 vu…

EPSS: 0.000 (3.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Element Synapse
Element-hq Synapse — versions < 1.152.1

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-45078?: CVE-2026-45078 is a medium-severity vulnerability in Element Synapse, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.5/10. Published 2026-05-28.
How severe is CVE-2026-45078?: Medium severity. CVSS v3 base score is 5.5 out of 10.