CVE-2026-55850CWE-79cross-site-scripting

CVE-2026-55850

published August 21, 2026

CVSS
5.3
EPSS
1%
Percentile
45.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS
5.3 · NONE
CVSS v4.0
5.3 · 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
EPSS
0.00547 · 45.1th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-08-21T23:17Z
References (4)
https://github.com/element-hq/element-web/commit/7949980a7e3c7e397d7afe899ef1b0563c417b0e · [email protected]https://github.com/element-hq/element-web/releases/tag/v1.12.22 · [email protected]https://github.com/element-hq/element-web/security/advisories/GHSA-wrcp-5v3v-3j6v · [email protected]https://www.machinespirits.com/advisory/563a17 · [email protected]
EPSS history
Timeline
  • 21 AUG 18:30Z
    Element Web: A malicious homeserver can inject HTML in Element Web using its homepage
    cvelistv5