{"identifier":"CVE-2026-45076","cve":{"id":"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.","published":"2026-05-28T17:16:31.590000+00:00","modified":"2026-10-26T13:10:00.140000+00:00","status":"Analyzed","score":5.1,"severity":"MEDIUM","vector":"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","cvss_version":"4.0","affected":[{"criteria":"cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:*","versionStartIncluding":"","versionStartExcluding":"","versionEndIncluding":"","versionEndExcluding":"1.152.1"}],"weaknesses":["CWE-20"],"references":[{"url":"https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v","source":"security-advisories@github.com","tags":["Vendor Advisory"]}],"kev":null,"kev_checked":true,"metrics":{"cvssMetricV40":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"4.0","vectorString":"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","baseScore":5.1,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"HIGH","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"LOW","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L","baseScore":2.7,"baseSeverity":"LOW","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"HIGH","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":1.2,"impactScore":1.4}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-06-02T14:51:22.795858Z","id":"CVE-2026-45076","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:element:synapse:*:*:*:*:*:*:*:*","versionEndExcluding":"1.152.1","matchCriteriaId":"30470335-8DE4-4DE9-84B0-09D11E4A2D70"}]}]}],"source":"nvd","retrieved_at":"2026-10-28T10:25:21.216710+00:00","exploited":false,"kev_stale":false,"products":["element / synapse"],"priority":{"label":"Assess exposure and vendor guidance","reasons":["No higher-priority signal is available in the current stored evidence."]},"epss":{"probability":0.00369,"percentile":0.30582,"date":"2026-10-27","stale":false},"version_assessment":null},"news":[],"campaigns":[],"domains":[{"domain":"github.com","source_url":"https://github.com/element-hq/synapse/security/advisories/GHSA-6qf2-7x63-mm6v","investigate_url":"https://investigate.aeglixmind.com/#github.com"}],"arsenal_url":"https://arsenal.aeglixmind.com/?cve=CVE-2026-45076","catalog_url":"https://cves.aeglixmind.com/cve/CVE-2026-45076","research_url":"https://investigate.aeglixmind.com/research/cve/CVE-2026-45076","coverage":{"news_candidates_checked":0,"campaign_candidates_checked":0,"bounded":false,"notice":"Exact CVE mentions in stored public excerpts and reviewed campaign content only. A mention is not proof of exploitation, attribution or tool suitability. Missing matches do not establish absence."}}