Envoy before 1.16.1 mishandles dropped and truncated datagrams, as demonstrated by a segmentation fault for a UDP packet size larger than 1…

published 2020-12-15 5 y ago modified 2026-09-08 2 mo ago also BIT-envoy-2020-35471 , EUVD-2020-23143

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.4%; EPSS 2.4% chance of exploitation in 30 days, percentile 84%
public exploits: 0; none known

Envoy before 1.16.1 mishandles dropped and truncated datagrams, as demonstrated by a segmentation fault for a UDP packet size larger than 1500.

Patch / fix

fixed in 2 distros 1 links 2

bitnami envoy 1.16.1
envoyproxy envoy 1.16.1

envoy-proxy Package Hub 15 SP3, openSUSE Leap 15.3 1.14.6-bp153.3.4.1

opensuse advisories openSUSE-SU-2022:0065-1

github.com/envoyproxy/envoy#14122 pull request
github.com/envoyproxy/envoy/compare/v1.16.0...v1.16.1 advisory

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-2020-35471 updated 2025-11-21 cvss 7.5

envoy: mishandling dropped and truncated datagrams leads to segfault and DoS

Red Hat OpenShift Service Mesh 1 servicemesh-proxy Red Hat OpenShift Service Mesh 2.0 servicemesh-proxy
affected: no fix planned “Will not fix”

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

2.39% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/envoyproxy/envoy/issues/14113 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
OSV	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
bitnami	envoy	<1.16.1	1.16.1

References

github.com /envoyproxy/envoy/pull/14122
patch, third-party-advisory, advisory
github.com /envoyproxy/envoy/compare/v1.16.0...v1.16.1
patch, third-party-advisory, advisory
github.com /envoyproxy/envoy/issues/14113
exploit, third-party-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2020-35471
web

Sources

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