Summary
SunEditor: Critical XSS vulnerability - sanitizer bypass
SUNEDITOR v2.47.10 appears to allow JavaScript execution through crafted namespaced HTML elements.
The sanitization logic does not fully remove executable event-handler attributes from certain custom/namespaced tags. As a result, an attacker may be able to inject HTML content that executes JavaScript when the rendered element is interacted with.
This behavior was observed after the changes introduced in this commit:
https://github.com/JiHong88/suneditor/commit/9ed405fb0de676e56cd0e6a13c19c103ad5948d3
Affected Version
Confirmed vulnerable:
- SUNEDITOR =<
2.47.10
Potentially affected:
- Previous versions, if the same sanitization logic is still present
Proof of Concept
The following payload preserves an executable event handler:
<a:b src="/x"><iframe src=javascript:alert(1)></iframe></a:b>
<p><a:b src="/x" onclick="document.body.style.background='red'">click</a:b></p>
Simplified PoC:
<a:b src="/x" onclick="console.log('XSS:',document.domain,document.cookie)">click</a:b>
<p><a:b src="/x" onmouseover="alert('XSS, '+document.domain)">📎 Click here for solutions</a:b></p>
Steps to Reproduce
- Open SUNEDITOR using version
2.47.10. - Insert the payload above into the editor.
- Save or render the generated content.
- Click the generated element.
- Observe that JavaScript is executed.
Technical Details
The issue appears to be related to incomplete handling of namespaced/custom HTML elements such as:
<a:b>
Event-handler attributes such as onclick can remain attached to these crafted elements and execute when interacted with.
This suggests that the sanitization process may not consistently normalize and validate custom or namespaced elements before applying attribute filtering.
Suggested Remediation
Possible mitigations include:
- Normalize DOM elements before sanitization.
- Explicitly reject or unwrap unknown/custom/namespaced tags.
- Strip all event-handler attributes from all elements, including unknown/custom elements.
- Re-validate sanitized output after browser DOM parsing.
- Add regression tests for namespaced/custom tag payloads.
Impact
This may allow an attacker to inject arbitrary JavaScript into rendered editor content.
Depending on how SUNEDITOR is integrated into an application, this could lead to:
- Stored XSS
- DOM manipulation
- Session theft
- Credential theft
- Account takeover actions performed in the victim’s browser context
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2026-59167 has a CVSS score of 10.0 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.47.11); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-59167? CVE-2026-59167 is a critical-severity cross-site scripting (XSS) vulnerability in suneditor (npm), affecting versions <= 2.47.10. It is fixed in 2.47.11. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2026-59167? CVE-2026-59167 has a CVSS score of 10.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of suneditor are affected by CVE-2026-59167? suneditor (npm) versions <= 2.47.10 is affected.
- Is there a fix for CVE-2026-59167? Yes. CVE-2026-59167 is fixed in 2.47.11. Upgrade to this version or later.
- Is CVE-2026-59167 exploitable, and should I be worried? Whether CVE-2026-59167 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-59167 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-59167? Upgrade
suneditorto 2.47.11 or later.