5.3

CVE-2026-55850: element-hq element-web Cross-site Scripting

CVSS: 5.3v4.0MediumDeferred
Published 21-08-2026Last modified 21-08-2026
Open JSON

Vulnerability summary

CVE-2026-55850 is a medium (CVSS 5.3) Cross-site Scripting vulnerability in element-hq element-web. EPSS estimates a 0.55% chance of exploitation in the next 30 days, higher than 44.7% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.55%
0%100%
Low · +0.23 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 21-08-2026
    PublishedVulnerability first disclosed.
  2. 21-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.55%

Chance of exploitation in the next 30 days

Percentile

45%

Versus all other CVEs

30-day change

+0.23 pp

From 0.32% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.55%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Element-hq1 product

1 vendor · 1 product

References

4 links