# CVE-2026-50572: Envoy use-after-free in HTTP external-authorization client

Source: https://junglewise.ai/threats/cve-2026-50572-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-2026-50572 · Severity: medium · CVSS 5.9 · Published 2026-09-21

Envoy is a proxy that handles network traffic for cloud applications. A flaw in its authorization checking component can cause the proxy to crash when processing rejected requests, potentially disrupting service availability. This occurs under normal production traffic conditions and could be exploited to cause denial of service.

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

## Quick answers

**Is CVE-2026-50572 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-50572 being exploited in the wild.

**How severe is CVE-2026-50572?** Medium severity, with a CVSS score of 5.9, 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-2026-50572?** 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-2026-50572 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-50572?** 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 HTTP external-authorization client in Envoy's RawHttpClientImpl retains a stale request callback after a request is rejected, leading to a use-after-free when onSuccess processes the authorization response. The vulnerability affects the ext_authz filter specifically; when the callback owner is destroyed before the response is processed, dereferencing the stale callback pointer causes a crash. Patches are available in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

## 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/8dacef38337aeffd62866b5c5910104b63b33db8](https://github.com/envoyproxy/envoy/commit/8dacef38337aeffd62866b5c5910104b63b33db8)
- [https://github.com/envoyproxy/envoy/commit/a49085623654e27e9ad6298928557644b849d7ce](https://github.com/envoyproxy/envoy/commit/a49085623654e27e9ad6298928557644b849d7ce)

## 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)