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CVE-2026-73512

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

HIGH
7.5
CVSS Score
Published: September 21, 2026 at 07:51 PM UTC
Updated: October 5, 2026 at 02:12 PM UTC
1 product affected across 1 vendorEnvoy

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Severity
HIGH7.5
Exploit prediction
EPSS 0.9%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Envoy· Envoyproxy
95%
v < 1.36.10v < 1.37.6v < 1.38.4v < 1.39.11.37.0 ≤ v < 1.37.61.38.0 ≤ v < 1.38.41.39.0 ≤ v < 1.39.1
Affected range stops below 1.36.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.37.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.38.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.39.1, so it looks safe — our inference, not a vendor statement

References (9)

x_refsource_CONFIRMExploitVendor AdvisoryMitigation
Source: cverecord
https://github.com/envoyproxy/envoy/security/advisories/GHSA-r6j2-mrm5-72mg
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/29dbaae4a9971011e2f1948acfaf383296e901ea
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/85495163fdc67364a5258bfe478c34a44f6428b4
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/c0e46dabc3ac286bbe608e9274776555911aadb9
x_refsource_MISCPatch
Source: cverecord
https://github.com/envoyproxy/envoy/commit/f2417eec2ff49abe243d484ded916fbc2faca38d
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-416

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