GHSA-w5cr-2qhr-jqc5
Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site
Blast Radius
agentsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A Reflected Cross-Site Scripting (XSS) vulnerability was discovered in the AI Playground's OAuth callback handler. The error_description query parameter was directly interpolated into an HTML script tag without proper escaping, allowing attackers to execute arbitrary JavaScript in the context of the victim's session.
Root cause
The OAuth callback handler in site/ai-playground/src/server.ts directly interpolated the authError value, sourced from the error_description query parameter, into an inline <script> tag.
Impact
An attacker could craft a malicious link that, when clicked by a victim, would:
- Steal user chat message history
- Access all LLM interactions stored in the user's session.
- Access connected MCP Servers
- Interact with any MCP servers connected to the victim's session (public or authenticated/private), potentially allowing the attacker to perform actions on the victim's behalf
Mitigation:
- PR: https://github.com/cloudflare/agents/pull/841
- Agents-sdk users should upgrade to
[email protected] - Developers using
configureOAuthCallbackwith custom error handling in their own applications should ensure all user-controlled input is escaped before interpolation.
Credits
Disclosed responsibly by Nishant Kumawat
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | agents | all versions | 0.3.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for agents. 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 agents to 0.3.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w5cr-2qhr-jqc5 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-w5cr-2qhr-jqc5 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-w5cr-2qhr-jqc5. 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-w5cr-2qhr-jqc5 in your dependencies?
O3 detects GHSA-w5cr-2qhr-jqc5 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.