CVE-2026-73512 Envoyproxy CVE debrief

Who should care

Defenders responsible for Envoy deployments should assess exposure and apply patches. The vulnerability can lead to a process crash, and Envoy versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected.

Why it matters

CVE-2026-73512 is a high-severity vulnerability in Envoy that can lead to a process crash. Defenders should prioritize assessing exposure and applying patches.

• Process crash due to invalid virtual dispatch
• Potential denial of service due to process crash

Technical summary

The vulnerability arises from Envoy's HttpDatagramHandler caching the current RequestDecoder when Capsule Protocol is enabled. During stream recreation, such as an internal redirect, the ActiveStream and EnvoyQuicServerStream are updated, but the handler's cached pointer is not. This can lead to a process crash when a subsequent HTTP/3 datagram calls decodeData through the freed decoder, causing invalid virtual dispatch.

Defensive priority

Defenders should prioritize assessing exposure and applying patches, as the vulnerability can lead to a process crash. Envoy versions prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1 are affected.

Recommended defensive actions

• Assess exposure by reviewing Envoy versions and configurations
• Apply patches in Envoy versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1
• Verify configurations and monitor for potential exploitation attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD vulnerability detail provide information on the vulnerability. Patches are available in Envoy versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1. Defenders should verify configurations, review Envoy versions and assess exposure, and monitor for potential exploitation attempts. The vulnerability arises from Envoy's HttpDatagramHandler caching the current RequestDecoder when Capsule Protocol is enabled, leading to a process crash. Stream recreation, including an internal redirect, replaces the ActiveStream and updates

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.