CVEvulnerability

CVE-2021-32778

7.5 HIGH Published 2021-08-24 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2021-08-24
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
5.8 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
CVSS 3.1 ([email protected])
7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0 ([email protected])
5.0 MEDIUM — AV:N/AC:L/Au:N/C:N/I:N/A:P
Weaknesses
CWE-834

Description

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.

Affected configurations

• envoyproxy envoy (>= 1.16.0 < 1.16.5) • envoyproxy envoy (>= 1.17.0 < 1.17.4) • envoyproxy envoy (>= 1.18.0 < 1.18.4) • envoyproxy envoy 1.19.0

Related

Weakness · CWE (1)

  • CWE-834 Excessive Iteration weakness

References