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CVE-2026-73512— Envoy: use-after-free in QUIC on internal redirects

Quick assessment

Affected

envoyproxy envoy

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Envoy 是一个专为云原生应用设计的开源边缘和服务代理。在 1.36.10、1.37.6、1.38.4 和 1.39.1 版本之前，当启用 Capsule 协议时，Envoy 的 HttpDatagramHandler 会缓存当前的 RequestDecoder。在流重建过程中（包括内部重定向），ActiveStream 会被替换，且 EnvoyQuicServerStream 会相应更新，但处理器的缓存指针并未得到更新。随后到来的 HTTP/3 数据报可能通过已被释放的解码器调用 decodeData，从而导致

CVSS 7.5 · High EPSS 0.87% · P59 Updated Sep 23, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 4

Vendor	Product	Version Range	Status
envoyproxy	envoy	`< 1.36.10`	affected
		`>= 1.37.0, < 1.37.6`	affected
		`>= 1.38.0, < 1.38.4`	affected
		`>= 1.39.0, < 1.39.1`	affected

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Vulnerability Information

Have questions about the vulnerability? See if Shenlong's analysis helps!

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Vulnerability Title

Envoy: use-after-free in QUIC on internal redirects

Source: CVE Program / CVE List V5

Vulnerability Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's HttpDatagramHandler caches the current RequestDecoder when Capsule Protocol is enabled. Stream recreation, including an internal redirect, replaces the ActiveStream and updates EnvoyQuicServerStream but does not update the handler's cached pointer. A subsequent HTTP/3 datagram can call decodeData through the freed decoder, causing invalid virtual dispatch and a process crash. The relevant scope boundary is that hTTP/3 datagrams and Capsule Protocol must be enabled, and the request must enter a stream-recreation path such as an internal redirect. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Source: CVE Program / CVE List V5

Vulnerability Type

释放后使用

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
envoyproxy	envoy	< 1.36.10	-

II. Public POCs for CVE-2026-73512

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-73512

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Patches & Fixes for CVE-2026-73512 (4)

Other References for CVE-2026-73512 (5)

🔗 Release v1.38.4 · envoyproxy/envoy · GitHub Read full article x_refsource_MISC
🔗 Release v1.37.6 · envoyproxy/envoy · GitHub Read full article x_refsource_MISC
🔗 Release v1.39.1 · envoyproxy/envoy · GitHub Read full article x_refsource_MISC
🔗 Release v1.36.10 · envoyproxy/envoy · GitHub Read full article x_refsource_MISC
🔗 use-after-free in QUIC on internal redirects · Advisory · envoyproxy/envoy · GitHub Read full article x_refsource_CONFIRM

https://www.cve.org/CVERecord?id=CVE-2026-73512

Same Patch Batch · envoyproxy · 2026-09-21 · 13 CVEs total

CVE-2026-73550	7.5 HIGH	Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy
CVE-2026-73553	7.5 HIGH	Envoy: RBAC Authorization Bypass via Path Parameters
CVE-2026-73513	7.5 HIGH	Envoy: oghttp2 upstream trailers incorrect handling
CVE-2026-73548	7.5 HIGH	Envoy: Cross-user response poisoning via a generic (non-WebSocket) HTTP upgrade on Envoy's
CVE-2026-73547	7.5 HIGH	Envoy ext_authz: request `:path` pseudoheader dereferenced w/o null check
CVE-2026-73552	7.5 HIGH	Envoy: HTTP RBAC safe_regex can fail open on RFC-valid obs-text header values
CVE-2026-73546	7.4 HIGH	Envoy: Stored XSS in Admin Stats Interface (/stats?format=html)
CVE-2026-48521	5.9 MEDIUM	Envoy: HTTP/3 connection pool selection null-derefs in ProdClusterManagerFactory::allocate
CVE-2026-50572	5.9 MEDIUM	Envoy: ext_authz - RawHttpClientImpl onSuccess 0x0 segfault
CVE-2026-73511	5.3 MEDIUM	Envoy: Potential path-matching/authentication bypass when using Envoy in combination with
CVE-2026-73549	5.3 MEDIUM	Envoy - Incomplete fix for CVE-2026-26310: copyInternetAddressAndPort crashes on scoped IP
CVE-2026-73551	5.3 MEDIUM	Envoy: Path normalization does not handle dot and dotdot segments with parameters

IV. Related Vulnerabilities

Same product: envoy

Same vendor: envoyproxy

Same weakness: CWE-416