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  4. CVE 2026 55850 element web a malicious homeserver can inject
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Back to active CVEs
Medium · CVSS 5.3CVE-2026-55850

Element Web: A malicious homeserver can inject HTML in Element Web using its homepageCVE-2026-55850

Answer in brief

CVE-2026-55850 records a Medium severity (CVSS 5.3) vulnerability in Element Web: A malicious homeserver can inject HTML in Element Web using its homepage. The current sources do not mark it as known exploited. The current feed maps element-hq/element-web (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 21, 2026Updated Aug 21, 2026Source checked Oct 6, 2026First seen by HOL Aug 21, 2026Material review Aug 21, 2026
Upstream Advisory

Key facts

Risk
Medium · CVSS 5.3
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps element-hq/element-web (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
element-hq/element-webgeneric<1.12.221.12.22

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for element-hq/element-web.
  2. 2Review the reported fix. Update element-hq/element-web to 1.12.22 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Aug 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Aug 21, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 21, 2026

Sources and claim methodology

  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • GitHub security advisorygithub.com
  • Source referencemachinespirits.com
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Joplin whiteboard card rendering allows CSS injection into application chromeAlso CWE-79
  • Newell Brands DYMO ID document parsing failing file type extension authentication checkSame generic ecosystem
  • Newell Brands DYMO ID parent directory open to path traversal through improper spheres of controlSame generic ecosystem
  • Bake filesystem entitlement consent is skipped for certain secret and oci-layout definitionsSame generic ecosystem
  • Improper validation of Ops Manager configuration in MongoDB Kubernetes OperatorSame generic ecosystem
  • GraphQL Tools has prototype pollution in well-established utility function `mergeDeep`Same generic ecosystem

Record context

Vulnerability class
XSS
EPSS
Not reported
CWE IDs
CWE-79
Source
CVE List V5
Source checked
Oct 6, 2026
References
4 linked sources
Open source record