# CVE-2026-124493: SunEditor stored cross-site scripting in DocumentType header rendering

Source: https://junglewise.ai/threats/cve-2026-124493-suneditor-before-3-4-0-contains-a-stored-cross-site-scripting  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-08. Updated: 2026-11-08  
License: CC BY 4.0 with a link back

CVE-2026-124493 · Severity: info · Published 2026-11-08

SunEditor is a JavaScript rich-text editor library used to build web-based document editors. A stored XSS vulnerability in the document header mode allows attackers to inject malicious scripts into document headers that execute when other users load the editor, enabling session cookie theft and account takeover.

Technologies: [JiHong88 SunEditor](https://junglewise.ai/threats/technologies/jihong88-suneditor). Vendors: [JiHong88](https://junglewise.ai/threats/vendors/jihong88).

## Quick answers

**Is CVE-2026-124493 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-124493 being exploited in the wild.

**How severe is CVE-2026-124493?** Informational severity, published 8 November 2026.

**Which products and versions are affected?** JiHong88 SunEditor before 3.4.0.

**Is there a fix for CVE-2026-124493?** Yes: fixed in 3.4.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-124493 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-124493?** Check whether you run JiHong88 SunEditor at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 3.4.0

## Technical details

The DocumentType constructor in SunEditor versions before 3.4.0 reads h1-h6 header elements' textContent (decoded plain text) and injects it directly into innerHTML without HTML escaping, causing the browser to parse HTML entities in the text as executable code. An attacker can pre-store HTML-encoded payloads in headers that become active HTML when the editor reinitializes; the vulnerability only affects configurations with type: 'document:header' set and is triggered automatically on page load without user interaction.

## Affected products

- JiHong88 SunEditor before 3.4.0

## Timeline

- 2026-10-23: disclosed
- 2026-11-08: advisory

## References

- [https://github.com/JiHong88/suneditor/security/advisories/GHSA-h9pq-57qf-vvfh](https://github.com/JiHong88/suneditor/security/advisories/GHSA-h9pq-57qf-vvfh)
- [https://www.vulncheck.com/advisories/suneditor-before-3.4.0-stored-xss-via-documenttype-header-textcontent](https://www.vulncheck.com/advisories/suneditor-before-3.4.0-stored-xss-via-documenttype-header-textcontent)

## Related threats

- [SunEditor stored XSS via HTML entity sanitizer bypass](https://junglewise.ai/threats/cve-2026-124494-suneditor-before-3-4-0-contains-a-stored-cross-site-scripting)
- [SunEditor stored XSS in link modal bookmark list](https://junglewise.ai/threats/cve-2026-124492-suneditor-before-3-4-0-contains-a-stored-cross-site-scripting)
- [SunEditor stored cross-site scripting in FileUpload plugin](https://junglewise.ai/threats/cve-2026-124491-suneditor-before-3-4-0-contains-a-stored-cross-site-scripting)
- [SunEditor stored cross-site scripting in html.clean iframe rebuild](https://junglewise.ai/threats/cve-2026-124422-suneditor-from-3-0-0-before-3-4-0-contains-a-stored-cross-site)