Vulnerability Details : CVE-2021-32778
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.
Vulnerability category: Denial of service
Products affected by CVE-2021-32778
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
- cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
- cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-32778
0.07%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 22 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-32778
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
5.0
|
MEDIUM | AV:N/AC:L/Au:N/C:N/I:N/A:P |
10.0
|
2.9
|
NIST | |
7.5
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
3.9
|
3.6
|
NIST | |
5.8
|
MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L |
3.9
|
1.4
|
GitHub, Inc. |
CWE ids for CVE-2021-32778
-
The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.Assigned by:
- nvd@nist.gov (Primary)
- security-advisories@github.com (Secondary)
References for CVE-2021-32778
-
https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history
Version history — envoy tag-v1.19.0 documentationRelease Notes;Vendor Advisory
-
https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc
Excessive CPU utilization when closing HTTP/2 streams · Advisory · envoyproxy/envoy · GitHubThird Party Advisory
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