CVE-2026-45076

Name: CVE-2026-45076
Creator: NVD / NIST
Published: 2026-05-28T17:16:31.59+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.1/10EPSS 0.37%

Last modified Jun 17, 2026

CVE-2026-45076 is a medium-severity vulnerability rated 5.1/10 on the CVSS scale. 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. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

2.7/10

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

CVSS 4.0

5.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.37%

28.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Element	Synapse	< 1.152.1

References

https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6vVendor Advisory

Timeline

Published: May 28, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-45076?

How severe is CVE-2026-45076?

CVE-2026-45076 has a CVSS score of 5.1/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2026-45076?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-45076?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST