CVE-2024-23323: Excessive CPU usage when URI template matcher is configured using regex in Envoy

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-02-09 · updated 2026-06-17
Weakness: CWE-400

Description

Envoy is a high-performance edge/middle/service proxy. The regex expression is compiled for every request and can result in high CPU usage and increased request latency when multiple routes are configured with such matchers. This issue has been addressed in released 1.29.1, 1.28.1, 1.27.3, and 1.26.7. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Affected products

envoyproxy envoy: from 1.26.0 before 1.26.7; from 1.27.0 before 1.27.3; from 1.28.0 before 1.28.1; from 1.29.0 before 1.29.1 — fixed in 1.26.7, 1.27.3, 1.28.1, 1.29.1

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.26.7, 1.27.3, 1.28.1, 1.29.1. Check the vendor advisory for mitigations.

References

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