CVE-2026-55850

medium

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.

References

https://www.machinespirits.com/advisory/563a17

https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v

https://github.com/element-hq/element-web/releases/tag/v1.12.22

https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e

Details

Source: Mitre, NVD

Published: 2026-08-21

Updated: 2026-08-21

Risk Information

CVSS v2

Base Score: 4.3

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N

Severity: Medium

CVSS v3

Base Score: 6.1

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Severity: Medium

CVSS v4

Base Score: 5.3

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

Severity: Medium

EPSS

EPSS: 0.00315