{"id":"CVE-2026-55850","state":"PUBLISHED","title":"Element Web: A malicious homeserver can inject HTML in Element Web using its homepage","description":"Element Web is a Matrix web client built using the Matrix React SDK. Prior to 1.12.22, EmbeddedPage in apps/web/src/components/structures/EmbeddedPage.tsx renders homeserver-supplied homepage content through dangerouslySetInnerHTML without passing it through sanitizedHtmlNode. A malicious homeserver can provide crafted HTML that Element Web renders on the homepage; the content security policy prevents JavaScript but not phishing HTML. This issue is fixed in version 1.12.22.","publishedAt":"2026-08-21T18:30:12.251Z","updatedAt":"2026-08-21T19:54:55.604Z","severity":{"score":5.3,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["element-hq element-web"],"affected":[{"vendor":"element-hq","product":"element-web","versions":[{"version":"< 1.12.22","status":"affected"}]}],"references":["https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v","https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e","https://github.com/element-hq/element-web/releases/tag/v1.12.22","https://www.machinespirits.com/advisory/563a17"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55850.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55850","state":"PUBLISHED","datePublished":"2026-08-21T18:30:12.251Z","dateUpdated":"2026-08-21T19:54:55.604Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-17T16:44:40.994Z"},"containers":{"cna":{"title":"Element Web: A malicious homeserver can inject HTML in Element Web using its homepage","descriptions":[{"lang":"en","value":"Element Web is a Matrix web client built using the Matrix React SDK. Prior to 1.12.22, EmbeddedPage in apps/web/src/components/structures/EmbeddedPage.tsx renders homeserver-supplied homepage content through dangerouslySetInnerHTML without passing it through sanitizedHtmlNode. A malicious homeserver can provide crafted HTML that Element Web renders on the homepage; the content security policy prevents JavaScript but not phishing HTML. This issue is fixed in version 1.12.22."}],"affected":[{"vendor":"element-hq","product":"element-web","versions":[{"version":"< 1.12.22","status":"affected"}]}],"references":[{"url":"https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v","name":"https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e","name":"https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e","tags":["x_refsource_MISC"]},{"url":"https://github.com/element-hq/element-web/releases/tag/v1.12.22","name":"https://github.com/element-hq/element-web/releases/tag/v1.12.22","tags":["x_refsource_MISC"]},{"url":"https://www.machinespirits.com/advisory/563a17","name":"https://www.machinespirits.com/advisory/563a17","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":5.3,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-21T18:30:12.251Z"},"source":{"advisory":"GHSA-wrcp-5v3v-3j6v","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T19:54:43.766385Z","id":"CVE-2026-55850","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T19:54:55.604Z"}}]}}}