CVE-2026-55850Network attack vector

Phishing via unsanitized homeserver homepage HTML

Published Aug 21, 2026 · Updated Aug 21, 2026

HTML injection in Element Web before 1.12.22 allows remote attackers controlling a homeserver to present phishing content on the homepage. EmbeddedPage passes homeserver-supplied homepage HTML to dangerouslySetInnerHTML without sanitizedHtmlNode filtering. Exploitation requires a user to open the homepage while connected to a malicious homeserver; the content security policy blocks JavaScript but leaves deceptive HTML effective.

CVSS severity5.3
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTML injection in Element Web before 1.12.22 allows remote attackers controlling a homeserver to present phishing content on the homepage. EmbeddedPage passes homeserver-supplied homepage HTML to dangerouslySetInnerHTML without sanitizedHtmlNode filtering. Exploitation requires a user to open the homepage while connected to a malicious homeserver; the content security policy blocks JavaScript but leaves deceptive HTML effective.

The record

CVE
CVE-2026-55850
Published
Aug 21, 2026
Updated
Aug 21, 2026
Vendor
Element HQ
Product
Element Web
Classifications
CWE-79, T1566
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.12.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Element HQ · Element Webversion=< 1.12.22

Published CVSS scores

5.3GitHub, Inc.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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1566Phishing

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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