CVE-2026-73512

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

Published Sep 21, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description No description is available for this CVE. 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.
Title envoy: envoy: HTTP/3 use-after-free when processing late datagrams Envoy: use-after-free in QUIC on internal redirects
References
Type Values Removed Values Added
First Time appeared Envoyproxy
Envoyproxy envoy
Vendors & Products Envoyproxy
Envoyproxy envoy
Type Values Removed Values Added
Description No description is available for this CVE.
Title envoy: envoy: HTTP/3 use-after-free when processing late datagrams
Weaknesses CWE-416
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Sep 22, 2026, 1:27 PM
Reserved
Aug 12, 2026, 7:00 PM
Status
Analyzed
Published
Sep 21, 2026, 8:17 PM
Modified
Oct 5, 2026, 2:12 PM
Severity
Important
Public date
Aug 26, 2026, 1:00 PM