CVE-2019-15226

Name: CVE-2019-15226
Creator: NVD / NIST
Published: 2019-10-09T16:15:14.687+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 65.39%

Last modified Jun 17, 2026

CVE-2019-15226 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Upon receiving each incoming request header data, Envoy will iterate over existing request headers to verify that the total size of the headers stays below a maximum limit. The implementation in versions 1.10.0 through 1.11.1 for HTTP/1.x traffic and all versions of Envoy for HTTP/2 traffic had O(n^2) performance characteristics. EPSS estimates a 65.39% chance of exploitation in the next 30 days.

Description

Upon receiving each incoming request header data, Envoy will iterate over existing request headers to verify that the total size of the headers stays below a maximum limit. The implementation in versions 1.10.0 through 1.11.1 for HTTP/1.x traffic and all versions of Envoy for HTTP/2 traffic had O(n^2) performance characteristics. A remote attacker may craft a request that stays below the maximum request header size but consists of many thousands of small headers to consume CPU and result in a denial-of-service attack.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

65.39%

99.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions
Envoyproxy	Envoy	1.0.0
Envoyproxy	Envoy	1.1.0
Envoyproxy	Envoy	1.2.0
Envoyproxy	Envoy	1.3.0
Envoyproxy	Envoy	1.4.0
Envoyproxy	Envoy	1.5.0
Envoyproxy	Envoy	1.6.0
Envoyproxy	Envoy	1.7.0
Envoyproxy	Envoy	1.7.1
Envoyproxy	Envoy	1.8.0
Envoyproxy	Envoy	1.9.0
Envoyproxy	Envoy	1.9.1
Envoyproxy	Envoy	1.10.0
Envoyproxy	Envoy	1.11.0
Envoyproxy	Envoy	1.11.1
Envoyproxy	Envoy	1.11.2

References

https://github.com/envoyproxy/envoy/commit/afc39bea36fd436e54262f150c009e8d72db5014Patch, Third Party Advisory
https://github.com/envoyproxy/envoy/commits/masterThird Party Advisory
https://github.com/envoyproxy/envoy/issues/8520Third Party Advisory
https://github.com/envoyproxy/envoy/commit/afc39bea36fd436e54262f150c009e8d72db5014Patch, Third Party Advisory
https://github.com/envoyproxy/envoy/commits/masterThird Party Advisory
https://github.com/envoyproxy/envoy/issues/8520Third Party Advisory

Timeline

Published: Oct 9, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-15226?

How severe is CVE-2019-15226?

CVE-2019-15226 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 65.39% probability of exploitation in the next 30 days.

How do I fix CVE-2019-15226?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-15226?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST