# CVE-2026-124493: SunEditor before 3.4.0 Stored XSS via DocumentType Header textContent


- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 8 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** GHSA-h9pq-57qf-vvfh, GHSA-pxmj-79fq-gv83

## What is CVE-2026-124493?

CVE-2026-124493 is a critical vulnerability in JiHong88 suneditor, published on 8 Nov 2026. 

### Official description

SunEditor before 3.4.0 contains a stored cross-site scripting vulnerability in the DocumentType constructor that injects header textContent into innerHTML without HTML escaping. Attackers can store entity-encoded HTML in h1-h6 headers that executes JavaScript when editors using document:header mode initialize, enabling session cookie theft.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-124493?


## How do I fix CVE-2026-124493?

No fix has been published for CVE-2026-124493 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-124493 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-124493 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-124493 and fix it if it is affected.

What it is: CVE-2026-124493 is a critical vulnerability in JiHong88 suneditor, published on 8 Nov 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-124493 exists.

Affected product: JiHong88 suneditor. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-124493/ (Markdown: https://insights.sbomify.com/CVE-2026-124493/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-124493
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124493
- OSV: https://osv.dev/vulnerability/CVE-2026-124493

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-124493/
Summaries are generated and may contain mistakes; the official description above is the record.