GHSA-3vv5-8xxp-4f55 — open-webui
MEDIUMGHSA-3vv5-8xxp-4f55 is a medium-severity (CVSS 6.5) CWE-346 vulnerability in open-webui. A fix is available for open-webui — see the affected versions and patch details below.
Open WebUI: Cross-origin postMessage confirmation bypass via action:submit
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-3vv5-8xxp-4f55.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-3vv5-8xxp-4f55 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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
The chat message listener allows non-same-origin input:prompt and action:submit messages, so an external site can set prompt text and trigger submitPrompt() in an authenticated victim session. I validated this with a cross-origin attacker page that auto-posted messages and caused unauthorized POST /api/v1/chats/new and POST /api/chat/completions requests containing attacker-controlled prompts. This enables cross-site forced actions and model/tool execution under victim privileges without consent.
Details
The chat page's window message listener in src/lib/components/chat/Chat.svelte processes message types including input:prompt and action:submit without adequately enforcing same-origin restrictions. Based on code around lines ~597-616, input text is set directly from event.data.text; action:submit proceeds to submitPrompt() on the current prompt. The logic does not apply a strict origin allowlist and permits non-same-origin control of the chat input and submission flow, leading to cross-origin command execution in the victim's authenticated UI context. As a result, backend API calls (e.g., POST /api/v1/chats/new, POST /api/chat/completions) are sent under victim credentials.
Normally, via the input:prompt:submit postMessage type, this results in a "Confirm Prompt from Embed" confirmation dialog:
However, combining the two other types, it is possible to achieve the same effect without this confirmation:
PoC
- Set up a local Open WebUI instance and log in to it, making sure a model is configured
- Host the following HTML anywhere and visit it (optionally change http://127.0.0.1:14000 to your instance Base URL):
<h1>Click anywhere</h1>
<script>
function sleep(ms) {
return new Promise(r => setTimeout(r, ms));
}
onclick = async () => {
w = window.open('http://127.0.0.1:14000');
await sleep(2000);
w.postMessage({ type: 'input:prompt', text: "INJECTED PROMPT" }, '*');
await sleep(500);
w.postMessage({ type: 'action:submit' }, '*');
}
</script>
- Click anywhere on the page, then notice without further interaction the "INJECTED PROMPT" is executed on the Open WebUI instance
Impact
Conditions required: The victim must be authenticated to Open WebUI in the browser (token cookie present).
This issue enables cross-site forced actions under the victim's identity. An attacker can silently inject prompts and trigger model/tool execution (e.g., code interpreter, web search, retrieval, terminal/tool servers) as the victim without confirmation.
Original Agent Report
<img width="400" alt="app aikido dev_ai-pentests_projects_116389_assessments_019d67d4-81c8-7dd2-bb9e-0a4a774b2c78_issues_sidebarIssue=20439940 (4)" src="https://github.com/user-attachments/assets/7b6521ed-d08b-446d-a918-103523d08a1e" />Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.9.6pip install --upgrade 'open-webui==0.9.6' |
Affected Products
open webuiopenwebuiDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update open-webui to 0.9.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-3vv5-8xxp-4f55 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.
Frequently Asked Questions
Is GHSA-3vv5-8xxp-4f55 in your dependencies?
Find it across PyPI, including transitive dependencies.