# CVE-2026-73547: Envoy null pointer dereference in ext_authz filter

Source: https://junglewise.ai/threats/cve-2026-73547-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-21. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-73547 · Severity: high · CVSS 7.5 · Published 2026-09-21

Envoy is an open source proxy used in cloud-native applications to route and filter traffic. The ext_authz filter, which applies authorization policies using query parameters, crashes when processing path-less CONNECT requests if query parameter mutation is configured. An unauthenticated attacker can trigger this crash to cause a denial of service by disrupting traffic through the proxy.

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

## Quick answers

**Is CVE-2026-73547 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-73547 being exploited in the wild.

**How severe is CVE-2026-73547?** High severity, with a CVSS score of 7.5, published 21 September 2026.

**Which products and versions are affected?** Envoy before 1.36.10, before 1.37.6, before 1.38.4, before 1.39.1.

**Is there a fix for CVE-2026-73547?** 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-2026-73547 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-73547?** Check whether you run 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

The ext_authz filter assumes request_headers_->Path() returns a non-null value when applying query_parameters_to_set or query_parameters_to_remove mutations. Path-less CONNECT requests return null for the path, causing a null pointer dereference in Filter::onComplete during query string parsing. The vulnerability requires the deployment to accept path-less CONNECT requests and configure ext_authz with query-parameter mutation; an unauthenticated downstream client can trigger the crash over the network.

## Affected products

- Envoy Envoy before 1.36.10, before 1.37.6, before 1.38.4, before 1.39.1

## Timeline

- 2026-09-21: disclosed

## References

- [https://github.com/envoyproxy/envoy/commit/064af2e61d0d1c421490d9e3e6e643c5d117ffe4](https://github.com/envoyproxy/envoy/commit/064af2e61d0d1c421490d9e3e6e643c5d117ffe4)
- [https://github.com/envoyproxy/envoy/commit/5f3b8e9b2b8a787a63202d35bb38820f3e9271fe](https://github.com/envoyproxy/envoy/commit/5f3b8e9b2b8a787a63202d35bb38820f3e9271fe)

## Related threats

- [Envoy authorization bypass via path parameter inconsistency](https://junglewise.ai/threats/cve-2026-73553-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)
- [Envoy path normalization bypass with semicolon parameters](https://junglewise.ai/threats/cve-2026-73551-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)
- [Envoy HTTP RBAC bypass via unsafe regex in headers](https://junglewise.ai/threats/cve-2026-73552-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)
- [Envoy HTTP/2 Host header denial of service](https://junglewise.ai/threats/cve-2026-73550-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)
- [Envoy scoped IPv6 address parsing denial of service](https://junglewise.ai/threats/cve-2026-73549-envoy-is-an-open-source-edge-and-service-proxy-designed-for-cloud)