CVE-2025-21620: Denoland Deno

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Deno is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults. When you send a request with the Authorization header to one domain, and the response asks to redirect to a different domain, Deno'sfetch() redirect handling creates a follow-up redirect request that keeps the original Authorization header, leaking its content to that second domain. This vulnerability is fixed in 2.1.2.

Affected products

• Denoland Deno: before 2.1.2 (fixed in 2.1.2)

Published 2025-01-06. Last modified 2026-06-17.