envoyproxy envoy up to 1.35.12/1.36.8/1.37.4/1.38.2 PATCH Request null pointer dereference

Summaryinfo

A vulnerability has been found in envoyproxy envoy up to 1.35.12/1.36.8/1.37.4/1.38.2 and classified as problematic. Impacted is an unknown function of the component PATCH Request Handler. This manipulation causes null pointer dereference. This vulnerability is registered as CVE-2026-47221. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in envoyproxy envoy up to 1.35.12/1.36.8/1.37.4/1.38.2. It has been declared as problematic. Affected by this vulnerability is an unknown part of the component PATCH Request Handler. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.18.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, the router filter contains a null pointer dereference vulnerability when handling HTTP 303 (See Other) internal redirects for body-less non-GET/HEAD requests. When a POST, PUT, DELETE, or PATCH request without a body is sent to a route configured with internal redirect policy that includes 303 in redirect_response_codes, and the upstream responds with HTTP 303, the redirect handling code attempts to drain a request body buffer that was never allocated. This results in a segmentation fault that crashes the entire Envoy process. When route configured with internal_redirect_policy including 303 in redirect_response_codes and upstream must return HTTP 303 response, an unauthenticated attacker can exploit this to cause complete denial of service, terminating all active connections. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-47221 since 05/19/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 1.35.13, 1.36.9, 1.37.5 or 1.38.3 eliminates this vulnerability.

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Productinfo

Type

• Firewall Software

Vendor

• envoyproxy

Name

• envoy

Version

• 1.35.0
• 1.35.1
• 1.35.2
• 1.35.3
• 1.35.4
• 1.35.5
• 1.35.6
• 1.35.7
• 1.35.8
• 1.35.9
• 1.35.10
• 1.35.11
• 1.35.12
• 1.36.0
• 1.36.1
• 1.36.2
• 1.36.3
• 1.36.4
• 1.36.5
• 1.36.6
• 1.36.7
• 1.36.8
• 1.37.0
• 1.37.1
• 1.37.2
• 1.37.3
• 1.37.4
• 1.38.0
• 1.38.1
• 1.38.2

License

• free

Website

• Product: https://github.com/envoyproxy/envoy/

CPE 2.3info

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CPE 2.2info

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