{"id":"BIT-envoy-2021-32778","summary":"Excessive CPU utilization when closing HTTP/2 streams","details":"Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions envoy’s procedure for resetting a HTTP/2 stream has O(N^2) complexity, leading to high CPU utilization when a large number of streams are reset. Deployments are susceptible to Denial of Service when Envoy is configured with high limit on H/2 concurrent streams. An attacker wishing to exploit this vulnerability would require a client opening and closing a large number of H/2 streams. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to reduce time complexity of resetting HTTP/2 streams. As a workaround users may limit the number of simultaneous HTTP/2 dreams for upstream and downstream peers to a low number, i.e. 100.","aliases":["CVE-2021-32778","GHSA-3xh3-33v5-chcc"],"modified":"2026-09-08T08:47:26.963903312Z","published":"2024-03-06T10:58:13.992Z","database_specific":{"cpes":["cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*","cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*"],"severity":"High"},"references":[{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc"},{"type":"ADVISORY","url":"https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-32778"}],"affected":[{"package":{"name":"envoy","ecosystem":"Bitnami","purl":"pkg:bitnami/envoy"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.16.0"},{"fixed":"1.16.5"},{"introduced":"1.17.0"},{"fixed":"1.17.4"},{"introduced":"1.18.0"},{"fixed":"1.18.4"},{"introduced":"1.19.0"},{"fixed":"1.19.1"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/envoy/BIT-envoy-2021-32778.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}],"schema_version":"1.9.0"}