CVE-2026-45076

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Published 2026-05-14 · Modified 2026-06-02

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CVSS v3

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CVSS v4 NEW

5.1

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

VIR risk

5.5

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.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

Mitigation details

Source: Debian Security Tracker · View original ↗ · DFSG

CVE-2026-45076 NameCVE-2026-45076 DescriptionSynapse 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. SourceCVE (at NVD; CERT, ENISA,…

CVE-2026-45076

Name	CVE-2026-45076
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
matrix-synapse (PTS)	forky, sid	1.152.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
matrix-synapse	source	(unstable)	1.152.1-1

Notes

https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v

Home - Debian Security - Source (Git)

Apply commands

text fix

Notes

https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v

OS impact

Debian Fixed 2 releases

Version	Status	Fixed in
sid	Fixed	`1.152.1-1`
forky	Fixed	`1.152.1-1`

Package impact

Ecosystem	Package	Vulnerable	Fixed
PyPI	matrix-synapse	`<1.152.1`	`1.152.1`
PIP	matrix-synapse	`< 1.152.1`	`1.152.1`

References

CWEs

CWE-20

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.