CVE-2024-30255

MEDIUM

Envoy < 1.26.8 - Denial of Service via HTTP/2 CONTINUATION Frame Flood

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2024-30255. PoCs published by lockness-Ko, blackmagic2023.

AI-analyzed exploit summary This repository contains a functional Go-based proof-of-concept exploit for CVE-2024-27316, targeting HTTP/2 servers with a denial-of-service (DoS) attack via malformed headers. The exploit leverages HPACK header compression to flood the target with crafted headers, causing resource exhaustion.

Description

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.

Exploits (2)

github WORKING POC 15 stars
by lockness-Ko · gopoc
https://github.com/lockness-Ko/CVE-2024-27316

This repository contains a functional Go-based proof-of-concept exploit for CVE-2024-27316, targeting HTTP/2 servers with a denial-of-service (DoS) attack via malformed headers. The exploit leverages HPACK header compression to flood the target with crafted headers, causing resource exhaustion.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: HTTP/2 servers (unencrypted or TLS)
No auth needed
Prerequisites: Network access to the target HTTP/2 server · Go 1.22.1 or compatible
devstral-2 · analyzed Feb 19, 2026 Full analysis →
nomisec WORKING POC 3 stars
by blackmagic2023 · poc
https://github.com/blackmagic2023/Envoy-CPU-Exhaustion-Vulnerability-PoC

This repository contains a functional Python script that demonstrates a CPU exhaustion vulnerability in Envoy by flooding the target with CONTINUATION frames. The PoC exploits a flaw in Envoy's HTTP/2 codec, which allows unlimited CONTINUATION frames even after exceeding header map limits.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Envoy (versions prior to 1.29.3, 1.28.2, 1.27.4, and 1.26.8)
No auth needed
Prerequisites: Network access to the target Envoy server · Python environment with socket and ssl libraries
devstral-2 · analyzed Feb 18, 2026 Full analysis →

References (4)

Core 4
Core References
Third Party Advisory, US Government Resource
https://www.kb.cert.org/vuls/id/421644
Patch, Third Party Advisory x_refsource_confirm
https://github.com/envoyproxy/envoy/security/advisories/GHSA-j654-3ccm-vfmm

Scores

CVSS v3 5.3
EPSS 0.8781
EPSS Percentile 99.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-390
Status published
Products (1)
envoyproxy/envoy < 1.26.8
Published Apr 04, 2024
Tracked Since Feb 18, 2026