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

Quick assessment

Affected

JiHong88 suneditor

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SunEditor 在 3.4.0 版本之前存在一个存储型跨站脚本（Stored XSS）漏洞。该漏洞源于构造函数将标题的直接注入到中，而未进行 HTML 转义。攻击者可以将经过实体编码的 HTML 代码注入到 h1 至 h6 标题中；当编辑器以模式初始化时，这些代码将执行 JavaScript，从而导致会话 Cookie 被窃取。

CVSS 9.3 · Critical Updated Nov 08, 2026

Possible ATT&CK Techniques 1 AI

T1059.007 · JavaScript

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Vulnerability Information

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Vulnerability Title

SunEditor before 3.4.0 Stored XSS via DocumentType Header textContent

Source: CVE Program / CVE List V5

Vulnerability 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.

Source: CVE Program / CVE List V5

CVSS Information

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

Source: CVE Program / CVE List V5

Vulnerability Type

在Web页面生成时对输入的转义处理不恰当(跨站脚本)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
JiHong88	suneditor	0 ~ 3.4.0	-

II. Public POCs for CVE-2026-124493

#	POC Description	Source Link	Shenlong Link

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No public POC found.

III. Intelligence Information for CVE-2026-124493

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Other References for CVE-2026-124493 (2)

https://github.com/JiHong88/suneditor/security/advisories/GHSA-h9pq-57qf-vvfh vendor-advisory
https://www.vulncheck.com/advisories/suneditor-before-3.4.0-stored-xss-via-documenttype-header-textcontent third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-124493

Same Patch Batch · JiHong88 · 2026-11-08 · 5 CVEs total

CVE-2026-124494	9.3 CRITICAL	SunEditor before 3.4.0 Stored XSS via &colon; Entity Sanitizer Bypass
CVE-2026-124492	7.6 HIGH	SunEditor before 3.4.0 Stored XSS via Link Modal Bookmark List
CVE-2026-124491	6.4 MEDIUM	SunEditor before 3.4.0 Stored XSS via FileUpload Plugin Filename
CVE-2026-124422	6.1 MEDIUM	SunEditor 3.0.0 before 3.4.0 Stored XSS via html.clean() Iframe Placeholder

IV. Related Vulnerabilities

Same product: suneditor

Same vendor: JiHong88

Same weakness: CWE-79