CVE-2024-30255: Envoyproxy Envoy

High severity, CVSS 7.5. EPSS: 87.8% chance of exploitation in the next 30 days.

Envoy is a cloud-native, open source edge and service proxy. The HTTP/2 protocol stack in Envoy versions prior to 1.29.3, 1.28.2, 1.27.4, and 1.26.8 are vulnerable to CPU exhaustion due to flood of CONTINUATION frames. Envoy's HTTP/2 codec allows the client to send an unlimited number of CONTINUATION frames even after exceeding Envoy's header map limits. This allows an attacker to send a sequence of CONTINUATION frames without the END_HEADERS bit set causing CPU utilization, consuming approximately 1 core per 300Mbit/s of traffic and culminating in denial of service through CPU exhaustion. Users should upgrade to version 1.29.3, 1.28.2, 1.27.4, or 1.26.8 to mitigate the effects of the CONTINUATION flood. As a workaround, disable HTTP/2 protocol for downstream connections.

Affected products

• Envoyproxy Envoy: before 1.26.8 (fixed in 1.26.8); from 1.27.0, before 1.27.4 (fixed in 1.27.4); from 1.28.0, before 1.28.2 (fixed in 1.28.2); from 1.29.0, before 1.29.3 (fixed in 1.29.3)

Published 2024-04-04. Last modified 2026-06-17.