What is CVE-2019-18836?

CVE-2019-18836 is a high-severity vulnerability in Envoyproxy Envoy, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2019-11-11.

How severe is CVE-2019-18836?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Envoyproxy Envoy

CVE-2019-18836

Envoy 1.12.0 allows a remote denial of service because of resource loops, as demonstrated by a single idle TCP connection being able to keep a worker thread in an infinite busy loop when continue_on_listener_filters_timeout is used."

Published 2019-11-11 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.019 (79.3th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.019 · newest: 0.019 · change: 0.000

Affected products

Envoyproxy Envoy — versions 1.12.0
Istio

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

groups.google.com/forum/
blog.envoyproxy.io (Vendor Advisory)
github.com/envoyproxy/envoy/security/advisories/GHSA-3xvf-4396-cj46 (Exploit, Third Party Advisory)
github.com/istio/istio/issues/18229 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2019-18836?: CVE-2019-18836 is a high-severity vulnerability in Envoyproxy Envoy, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2019-11-11.
How severe is CVE-2019-18836?: High severity. CVSS v3 base score is 7.5 out of 10.