Low severity · published May 28, 2026
CVE-2026-45076
Synapse pagination denial of service
2.7
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 31% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SY
synapse · element-hq
< 1.152.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45076
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45076
Vendor Advisory
https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v
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