{"cve":"CVE-2019-15226","nvd":{"published":"2019-10-09T16:15:14.687","modified":"2026-06-17T02:19:53.463","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-400"],"references":["https://github.com/envoyproxy/envoy/commit/afc39bea36fd436e54262f150c009e8d72db5014","https://github.com/envoyproxy/envoy/commits/master","https://github.com/envoyproxy/envoy/issues/8520","https://github.com/envoyproxy/envoy/commit/afc39bea36fd436e54262f150c009e8d72db5014","https://github.com/envoyproxy/envoy/commits/master"],"products":["envoyproxy:envoy"],"source":"nvd","synced_at":"2026-10-19T20:59:10.855360465+00:00"},"epss":{"cve":"CVE-2019-15226","score":0.64517,"percentile":0.99238,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}