CVE-2026-47207

Analyzed Analyzed - Analysis Complete

Use-After-Free in Envoy Proxy Due to Malformed gRPC ProcessingResponse

Publication date: 2026-06-26

Last updated on: 2026-06-27

Assigner: GitHub, Inc.

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, Envoy crashes if an ext_proc server sends a single gRPC message containing multiple, specially crafted ProcessingResponse messages. This can occur when the first response in the batch causes the gRPC stream object to be destroyed, leading to a use-after-free error when Envoy attempts to process subsequent responses in the same gRPC message. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-06-26

Last Modified

2026-06-27

Generated

2026-07-17

AI Q&A

2026-06-26

EPSS Evaluated

2026-07-15

NVD

CVE-2026-47207

EUVD

EUVD-2026-39826

Affected Vendors & Products

Vendor	Product	Version / Range
envoyproxy	envoy	From 1.37.0 (inc) to 1.37.5 (exc)
envoyproxy	envoy	From 1.38.0 (inc) to 1.38.3 (exc)
envoyproxy	envoy	From 1.34.0 (inc) to 1.35.13 (exc)
envoyproxy	envoy	From 1.36.0 (inc) to 1.36.9 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This vulnerability affects Envoy Proxy versions between 1.34.0 and 1.39 (excluding patched versions). It occurs when an ext_proc server sends a single gRPC message containing multiple specially crafted ProcessingResponse messages. The first response in the batch causes the gRPC stream object to be destroyed, which leads to a use-after-free error when Envoy tries to process the subsequent responses in the same message. This results in Envoy crashing.

Detection Guidance

This vulnerability occurs when an ext_proc server sends a single gRPC message containing multiple specially crafted ProcessingResponse messages that cause Envoy to crash due to a use-after-free error.

Detection would involve monitoring Envoy logs and network traffic for crashes or abnormal terminations related to the ext_proc filter and gRPC messages.

Specifically, you can look for crash logs referencing AsyncStreamImpl::onData() or callbacks_.onReceiveMessageRaw() in Envoy.

Network capture tools could be used to inspect gRPC messages sent to Envoy, checking for messages containing multiple ProcessingResponse messages in a single gRPC message.

However, no specific commands or detection scripts are provided in the available resources.

Impact Analysis

An attacker can exploit this vulnerability by sending a specially crafted gRPC message with multiple ProcessingResponse messages through an ext_proc filter. This causes Envoy to crash due to a use-after-free error, resulting in a Denial of Service (DoS). The impact is that the service relying on Envoy could become unavailable or unstable.

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Mitigation Strategies

The primary mitigation is to upgrade Envoy to one of the patched versions where this vulnerability is fixed.

Upgrade to Envoy version 1.35.13, 1.36.9, 1.37.5, or 1.38.3 or later.

Until the upgrade can be performed, consider disabling or restricting the use of the ext_proc filter to prevent processing of potentially malicious gRPC messages.

Monitor Envoy for crashes and investigate any abnormal terminations related to gRPC ext_proc messages.

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