# CVE-2026-47207: Envoy use-after-free in ext_proc filter gRPC message handling

Source: https://junglewise.ai/threats/cve-2026-47207-envoy-use-after-free-in-ext-proc-filter-grpc-message-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-26. Updated: 2026-06-26  
License: CC BY 4.0 with a link back

CVE-2026-47207 · Severity: medium · CVSS 6.5 · Published 2026-06-26

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.

Technologies: [Envoy Proxy Envoy](https://junglewise.ai/threats/technologies/envoy). Vendors: [Envoy Proxy](https://junglewise.ai/threats/vendors/envoy-proxy).

## Quick answers

**Is CVE-2026-47207 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47207 being exploited in the wild.

**How severe is CVE-2026-47207?** Medium severity, with a CVSS score of 6.5, published 26 June 2026.

**Which products and versions are affected?** 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.

**Is there a fix for CVE-2026-47207?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-47207 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-47207?** Check whether you run Envoy Proxy Envoy at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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

## References

- [https://github.com/envoyproxy/envoy/security/advisories/GHSA-68cv-hq5f-g6xv](https://github.com/envoyproxy/envoy/security/advisories/GHSA-68cv-hq5f-g6xv)

## Related threats

- [Envoy HTTP upgrade connection poisoning](https://junglewise.ai/threats/cve-2026-73548-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)
- [Envoy use-after-free in HTTP OAuth2 filter](https://junglewise.ai/threats/cve-2026-48090-envoy-use-after-free-in-http-oauth2-filter)
- [Envoy denial of service via NULL pointer dereference in log formatting](https://junglewise.ai/threats/cve-2026-47220-envoy-denial-of-service-via-null-pointer-dereference-in-log)
- [Envoy Use-After-Free in ext_authz filter during stream teardown](https://junglewise.ai/threats/cve-2026-47205-envoy-use-after-free-in-ext-authz-filter-during-stream-teardown)
- [Envoy HTTP/3 to HTTP/1 request smuggling in downstream translation](https://junglewise.ai/threats/cve-2026-48743-envoy-http-3-to-http-1-request-smuggling-in-downstream)