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Vulnerability record · CVE-2019-18801 · published 13 December 2019

CVE-2019-18801: Envoyproxy envoy out-of-bounds write vulnerability

Envoyproxy · Envoy

An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1. This may be used to corrupt nearby heap contents (leading to a query-of-death scenario) or may be used to bypass Envoy's access control mechanisms such as path based routing. An attacker can also modify requests from other users that happen to be proximal temporally and spatially.

9.8 CVSS 3.1 Critical EPSS 2.5% · top 15.9% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score, v2 7.5
2.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
10References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1. This may be used to corrupt nearby heap contents (leading to a query-of-death scenario) or may be used to bypass Envoy's access control mechanisms such as path based routing. An attacker can also modify requests from other users that happen to be proximal temporally and spatially.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://access.redhat.com/errata/RHSA-2019:4222 Third Party Advisory
https://blog.envoyproxy.io Product
https://github.com/envoyproxy/envoy/commits/master Patch
https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rppp ExploitThird Party Advisory
https://groups.google.com/forum/#%21forum/envoy-users
https://access.redhat.com/errata/RHSA-2019:4222 Third Party Advisory
https://blog.envoyproxy.io Product
https://github.com/envoyproxy/envoy/commits/master Patch
https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rppp ExploitThird Party Advisory
https://groups.google.com/forum/#%21forum/envoy-users

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2019-18801), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.