What is CVE-2025-4820?

CVE-2025-4820 is a medium-severity vulnerability in Cloudflare Quiche, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.3/10. Published 2025-06-18.

How severe is CVE-2025-4820?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Resource exhaustion in Cloudflare Quiche

CVE-2025-4820

Impact Cloudflare quiche was discovered to be vulnerable to incorrect congestion window growth, which could cause it to send data at a rate faster than the path might actually support. An unauthenticated remote attacker can exploit the v…

EPSS: 0.007 (47.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Cloudflare Quiche — versions <0.24.4

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

cna@cloudflare.com (Vendor Advisory)

Frequently asked questions

What is CVE-2025-4820?: CVE-2025-4820 is a medium-severity vulnerability in Cloudflare Quiche, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.3/10. Published 2025-06-18.
How severe is CVE-2025-4820?: Medium severity. CVSS v3 base score is 5.3 out of 10.