Executive brief
Envoy is a widely used service proxy that manages network traffic for cloud-native applications. A vulnerability exists where a malicious or misconfigured external processing server can cause Envoy to crash by sending specifically formatted messages. This results in a denial-of-service (DoS) condition, potentially disrupting application availability and network traffic flow.
Technical details
A use-after-free vulnerability exists in Envoy's ext_proc filter implementation within the AsyncStreamImpl::onData() function. When an external processing server sends a single gRPC message containing multiple ProcessingResponse messages, the first response may trigger the destruction of the gRPC stream object (callbacks_). If Envoy attempts to process subsequent responses within the same gRPC message, it accesses the now-freed object, leading to a crash. This requires the attacker to control or compromise an ext_proc server. The issue is fixed in versions 1.35.13, 1.36.9, 1.37.5, and 1.38.3.
Affected products
- Envoy Proxy Envoy >= 1.34.0, < 1.35.13; >= 1.36.0, < 1.36.9; >= 1.37.0, < 1.37.5; >= 1.38.0, < 1.38.3
Timeline
- 2026-06-23: advisory: GitHub Security Advisory published
- 2026-06-26: disclosed: CVE published to NVD