Bug 2512088 (CVE-2026-73512)

Summary: CVE-2026-73512 envoy: envoy: HTTP/3 use-after-free when processing late datagrams
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: kaycoth, security-response-team
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Envoy. A remote attacker can cause a Denial of Service (DoS) by triggering a use-after-free memory vulnerability in the QUIC HTTP datagram handler. When HTTP/3 datagrams and the Capsule Protocol are enabled, stream recreation events such as internal redirects can leave the handler referencing a stream decoder that has already been freed. Subsequent datagrams attempting to access this invalid memory cause the application to crash.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Deadline: 2026-08-26   

Description OSIDB Bzimport 2026-08-06 15:01:17 UTC 
A use-after-free in the QUIC HTTP datagram handler. A request that used the Capsule Protocol could have its stream decoder destroyed or replaced while late HTTP/3 datagrams still referenced it, for example following an internal redirect or stream completion. The fix replaces the cached raw decoder pointer with a weak decoder provider.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (7.5)

Embargoed until 2026-08-26 13:00 GMT per Envoy upstream disclosure. PSIRTSUPT-21132.