CVE-2021-32778

Excessive CPU utilization when closing HTTP/2 streams

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.

Category

5.8
CVSS
Severity: Medium
CVSS 3.1 •
CVSS 2.0 •
EPSS 0.07%
Vendor Advisory envoyproxy.io
Affected: envoyproxy envoy
Published at:
Updated at:

References

Link Tags
https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history release notes vendor advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc third party advisory

Frequently Asked Questions

What is the severity of CVE-2021-32778?
CVE-2021-32778 has been scored as a medium severity vulnerability.
How to fix CVE-2021-32778?
To fix CVE-2021-32778, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-32778 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-32778 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-32778?
CVE-2021-32778 affects envoyproxy envoy.
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