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 kee…

published 2019-11-11 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-8537

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.9%; EPSS 1.9% chance of exploitation in 30 days, percentile 80%
public exploits: 0; none known

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."

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-18836 updated 2025-11-21 cvss 7.5

envoy: excessive iteration due to listener filter timeout leads to DoS

Red Hat OpenShift Service Mesh 1 envoy
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.94% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xvf-4396-cj46 referenced PoC, tagged "exploit" by a source, unverified
github.com https://github.com/istio/istio/issues/18229 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

CWE-835 Loop with Unreachable Exit Condition

References

github.com /envoyproxy/envoy/security/advisories/GHSA-3xvf-4396-cj46
exploit, third-party-advisory
github.com /istio/istio/issues/18229
exploit, third-party-advisory
blog.envoyproxy.io
vendor-advisory
groups.google.com /forum/#%21forum/envoy-users

Sources

CVE List CVE-2019-18836
NVD CVE-2019-18836

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary