CVE-2026-45078 | BDVDB-2026-336200 Detail

element-hqsynapse

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.

Impact#

Per CVSS v4.0: confidentiality impact none, integrity impact none, availability impact high. Attack vector: local.

Weaknesses#

CWE-770 Allocation of Resources Without Limits or Throttling

References#

https://github.com/element-hq/synapse/security/advisories/GHSA-8q93-326v-3m7g

Exploit#

No public exploit known

History#

Version 12026-05-28Record published in the CVE List.
Version 22026-05-29Most recent update recorded in the CVE List.

Published

Published: 2026-05-28
Last modified: 2026-05-29

Vendor information

Vendor: element-hq
Product: synapse

All element-hq vulnerabilities

Score

6.8 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 2.5.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 1.152.1
Fixed
Not stated

Scoring System

CVSS v4.0

6.8 Medium

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

Metric breakdown
Attack Vector	Local
Attack Complexity	Low
Attack Requirements	None
Privileges Required	Low
User Interaction	None
Vulnerable System Confidentiality	None
Vulnerable System Integrity	None
Vulnerable System Availability	High
Subsequent System Confidentiality	None
Subsequent System Integrity	None
Subsequent System Availability	None

CVSS v3.1

Not available

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).