Information disclosure in Denoland Deno

CVE-2025-21620

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.

Vulnerability class: Information Disclosure

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (41.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-21620: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-21620?
CVE-2025-21620 is a high-severity vulnerability in Denoland Deno, classified under Information Disclosure. CVSS score: 7.5/10. Published 2025-01-06.
How severe is CVE-2025-21620?
High severity. CVSS v3 base score is 7.5 out of 10.