GHSA-xc4x-2452-5gc9
GHSA-xc4x-2452-5gc9 is a Cross-site Scripting (XSS) vulnerability in sillytavern. O3 Security confirms whether GHSA-xc4x-2452-5gc9 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SillyTavern has a reflected XSS vulnerability in the CORS proxy middleware
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-xc4x-2452-5gc9.
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.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
sillytavernnpmDescription
Resolution
Fixed in SillyTavern 1.18.0: a user-provided URL is no longer reflected in the HTTP response body.
Overview
- Vulnerability Type: XSS
- Affected Location:
src/middleware/corsProxy.js:40 - Trigger Scenario: reflected XSS in CORS proxy error response
Root Cause
When fetch(url) throws, the code sends:
res.status(500).send('Error occurred while trying to proxy to: ' + url + ' ' + error).
The url value is attacker-controlled (req.params.url) and is not HTML-escaped before rendering.
Source-to-Sink Chain
- Source (user-controlled input)
- Entry point:
GET /proxy/:url(*)
- Data flow
- Code analysis shows concrete propagation into this sink:
- vulnerability title:
Reflected XSS in CORS proxy error response - sink location reached by attacker-controlled input:
src/middleware/corsProxy.js:40
- vulnerability title:
- The same sink behavior is confirmed by controlled execution observations.
- Sink (dangerous operation)
- Sink location:
src/middleware/corsProxy.js:40 - Vulnerable behavior: reflected XSS in CORS proxy error response
Exploitation Preconditions
- The attacker can inject controllable content into a rendered response.
- The vulnerable rendering context does not apply strict output encoding/sanitization.
- A victim user opens the affected page or response.
Risk
This issue enables script execution in the victim context and can compromise session or data integrity.
Impact
An attacker may run arbitrary JavaScript in the victim context, steal tokens, and manipulate user-visible behavior.
Remediation
- Never concatenate raw user input into HTML error responses.
- If URL echo is required, HTML-escape it or force plain-text output.
- Re-enable/strengthen CSP to reduce reflected injection impact.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | sillytavern | all versions | 1.18.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sillytavern. 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 sillytavern to 1.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xc4x-2452-5gc9 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-xc4x-2452-5gc9 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-xc4x-2452-5gc9. 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-xc4x-2452-5gc9 in your dependencies?
O3 detects GHSA-xc4x-2452-5gc9 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.