GHSA-w5cr-2qhr-jqc5 — agents
Fix: cloudflare/agents#841GHSA-w5cr-2qhr-jqc5 is a security vulnerability in agents. A fix is available for agents — see the affected versions and patch details below.
Cloudflare Agents has a Reflected Cross-Site Scripting (XSS) vulnerability in AI Playground site
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.
agentsnpmDescription
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 | 0.3.10npm install agents@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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-w5cr-2qhr-jqc5 can be triaged on real exposure rather than presence alone.
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 Security finds GHSA-w5cr-2qhr-jqc5 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.