CVE-2023-27492: Envoy may crash when a large request body is processed in Lua filter

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-04-04 · updated 2026-06-17
Weakness: CWE-770

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, the Lua filter is vulnerable to denial of service. Attackers can send large request bodies for routes that have Lua filter enabled and trigger crashes. As of versions versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, Envoy no longer invokes the Lua coroutine if the filter has been reset. As a workaround for those whose Lua filter is buffering all requests/ responses, mitigate by using the buffer filter to avoid triggering the local reply in the Lua filter.

Affected products

envoyproxy envoy: before 1.22.9; from 1.23.0 before 1.23.6; from 1.24.0 before 1.24.4; from 1.25.0 before 1.25.3 — fixed in 1.22.9, 1.23.6, 1.24.4, 1.25.3

How to fix

Upgrade to a fixed version: envoyproxy envoy 1.22.9, 1.23.6, 1.24.4, 1.25.3. Check the vendor advisory for mitigations.

References

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