Vulnerability · Published Aug 24, 2021 · Assigned by GitHub_M
CVE-2021-32778Excessive CPU utilization when closing HTTP/2 streams
Medium 5.8
In plain English
A medium-severity security flaw in envoy from envoyproxy. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 69% of all known vulnerabilities).
Official 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 products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| envoyproxy | envoy | >= 1.19.0, < 1.19.1>= 1.18.0, < 1.18.4>= 1.17.0, < 1.17.4>= 1.16.0, < 1.16.5 |
Weakness: CWE-834 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L