Is CVE-2026-45076 in the CISA KEV catalog?

No. CVE-2026-45076 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-45076?

CVE-2026-45076 has a CVSS v3 base score of 2.7 (LOW).

What is the EPSS score for CVE-2026-45076?

CVE-2026-45076 has an EPSS score of 0.37% (29th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-45076?

Upgrade matrix-synapse on debian unstable to 1.152.1-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-45076

LOW

2.7

CVSS v3

NVD

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.

CWE-20Improper Input Validation

How to fix

Remediation Available

matrix-synapseDebian

Fixed in:1.152.1-1CVE-2026-45076

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredHigh

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.37%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2021-45105	Medium	5.9	100%	-	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2018-7600	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-3452	High	7.5	100%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-04.