cvedb.io
CVE-2025-4821
HIGH · CVSS 7.5
EPSS exploitation probability: 0%
Published 2025-06-18T16:15:28.527 · Last modified 2026-06-17T09:34:05.217

Summary

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 vulnerability by first completing a handshake and initiating a congestion-controlled data transfer towards itself. Then, it could manipulate the victim's congestion control state by sending ACK frames covering a large range of packet numbers (including packet numbers that had never been sent); see RFC 9000 Section 19.3. The victim could grow the congestion window beyond typical expectations and allow more bytes in flight than the path might really support. In extreme cases, the window might grow beyond the limit of the internal variable's type, leading to

Affected products

cloudflare — quiche

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.