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.
INFO
Published Date :
Aug. 24, 2021, 9:15 p.m.
Last Modified :
Nov. 21, 2024, 6:07 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 2.0 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update to Envoy version 1.16.5, 1.17.4, 1.18.4, or 1.19.1 or later.
- Consider limiting the number of simultaneous HTTP/2 streams for upstream and downstream peers.
Public PoC/Exploit Available at Github
CVE-2021-32778 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-32778.
| URL | Resource |
|---|---|
| https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc | Third Party Advisory |
| 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 |
| https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history | Release Notes Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-32778 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-32778
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Automatic monitor github cve using Github Actions
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2021-32778 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-32778 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Nov. 21, 2024
Action Type Old Value New Value Added Reference https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc Added Reference https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history -
CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Reanalysis by [email protected]
Jun. 15, 2022
Action Type Old Value New Value Changed CPE Configuration OR *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.16.0 up to (excluding) 1.16.5 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.17.0 up to (excluding) 1.17.4 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.18.0 up to (excluding) 1.18.4 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.19.0 up to (excluding) 1.91.1 OR *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.16.0 up to (excluding) 1.16.5 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.17.0 up to (excluding) 1.17.4 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.18.0 up to (excluding) 1.18.4 *cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:* -
Initial Analysis by [email protected]
Sep. 01, 2021
Action Type Old Value New Value Added CVSS V2 NIST (AV:N/AC:L/Au:N/C:N/I:N/A:P) Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc No Types Assigned https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc Third Party Advisory Changed Reference Type https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history No Types Assigned https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history Release Notes, Vendor Advisory Added CWE NIST CWE-834 Added CPE Configuration OR *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.16.0 up to (excluding) 1.16.5 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.17.0 up to (excluding) 1.17.4 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.18.0 up to (excluding) 1.18.4 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.19.0 up to (excluding) 1.91.1
Vulnerability Scoring Details
Base CVSS Score: 7.5
Base CVSS Score: 5
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.07 }} -0.00%
score
0.22107
percentile