CVE-2019-15226
HighUpon 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.
Published Oct 9, 2019 · Updated Aug 7, 2026
Key Facts
Patch immediately- CVE-2019-15226 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Envoy (Envoyproxy).
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 65% probability of exploitation in the next 30 days.
- Fixed versions are available, including Envoy 1.13.1-1.ph1, Envoy 1.13.1-1.ph2.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
65%
Higher than 99.2% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
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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.
Affected Products
18 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| EnvoyEnvoyproxy | 1.0.0, 1.1.0, 1.10.0, 1.11.0, 1.11.1, 1.11.2, 1.2.0, 1.3.0 | 1.13.1-1.ph1 |
Patched Releases
Envoy
1.13.1-1.ph1, 1.13.1-1.ph2
Timeline
Publicly disclosed
Oct 9, 2019
Last updated
Aug 7, 2026
Weakness Type
- CWE-400 Uncontrolled Resource Consumption
References
FAQ
Common Questions.
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.
Affected: Envoy (Envoyproxy) versions 1.0.0, 1.1.0, 1.10.0, 1.11.0, 1.11.1, 1.11.2, 1.2.0, 1.3.0. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Envoy 1.13.1-1.ph1, Envoy 1.13.1-1.ph2.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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