Advisories for Npm/Agents package

2026

Cloudflare Agents is Vulnerable to Reflected Cross-Site Scripting in the AI Playground's OAuth callback handler

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 …

Cloudflare Agents SDK has Insecure Direct Object Reference (IDOR) via Header-Based Email Routing

An Insecure Direct Object Reference (CWE-639) has been found to exist in createHeaderBasedEmailResolver() function within the Cloudflare Agents SDK. The issue occurs because the Message-ID and References headers are parsed to derive the target agentName and agentId without proper validation or origin checks, allowing an external attacker with control of these headers to route inbound mail to arbitrary Durable Object instances and namespaces.