Use After Free in Envoyproxy Envoy

CVE-2026-47207

Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.34.0 until 1.35.13, 1.36.9, 1.37.5, and 1.38.3, Envoy crashes if an ext_proc server sends a single gRPC message containing multiple, specially crafted ProcessingResponse messages. This can occur when the first response in the batch causes the gRPC stream object to be destroyed, leading to a use-after-free error when Envoy attempts to process subsequent responses in the same gRPC message. This vulnerability is fixed in 1.35.13, 1.36.9, 1.37.5, and 1.38.3.

Vulnerability class: Use-After-Free

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (36.1th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-47207: held from 0.004 to 0.004.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

  • Envoyproxy Envoy — versions >= 1.38.0, < 1.38.3, >= 1.37.0, < 1.37.5, >= 1.36.0, < 1.36.9

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-47207?
CVE-2026-47207 is a medium-severity vulnerability in Envoyproxy Envoy, classified under Use After Free. CVSS score: 6.5/10. Published 2026-06-26.
How severe is CVE-2026-47207?
Medium severity. CVSS v3 base score is 6.5 out of 10.