# CVE-2026-47220: Envoy denial of service via NULL pointer dereference in log formatting

Source: https://junglewise.ai/threats/cve-2026-47220-envoy-denial-of-service-via-null-pointer-dereference-in-log  
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-2026-47220 · Severity: high · CVSS 7.5 · Published 2026-06-26

Envoy, a widely used tool for managing network traffic in cloud environments, is vulnerable to a flaw that can cause the service to crash. If the system is configured to log specific server names and receives a request missing certain expected information, the entire proxy service may shut down. This results in a denial-of-service, potentially cutting off access to applications and services relying on Envoy for connectivity.

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

## Quick answers

**Is CVE-2026-47220 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-47220 being exploited in the wild.

**How severe is CVE-2026-47220?** High severity, with a CVSS score of 7.5, published 26 June 2026.

**Which products and versions are affected?** Envoy Proxy Envoy 1.37.0 to 1.37.4, 1.38.0 to 1.38.2.

**Is there a fix for CVE-2026-47220?** 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-2026-47220 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-47220?** 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 NULL pointer dereference (CWE-476) exists in Envoy's handling of the %REQUESTED_SERVER_NAME(X:Y)% log format specifier. When host-related fallback options such as HOST_FIRST or SNI_FIRST are enabled, the handler fails to validate the presence of the :authority or x-envoy-original-host headers. If a request is received where these headers are missing or null, Envoy attempts to access the null memory address, resulting in a segmentation fault and service crash. This is reachable over the network without authentication. The issue is resolved in versions 1.37.5 and 1.38.3.

## Affected products

- Envoy Proxy Envoy 1.37.0 to 1.37.4, 1.38.0 to 1.38.2

## Timeline

- 2026-06-23: advisory: GitHub Security Advisory published
- 2026-06-26: disclosed: NVD publication date

## References

- [https://github.com/envoyproxy/envoy/security/advisories/GHSA-j9wh-4qfm-wf2v](https://github.com/envoyproxy/envoy/security/advisories/GHSA-j9wh-4qfm-wf2v)

## 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 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)
- [Envoy heap buffer overflow in TcpStatsdSink](https://junglewise.ai/threats/cve-2026-48706-envoy-heap-buffer-overflow-in-tcpstatsdsink)