Vulnerability Report

CVE-2021-32778

Title: Envoy HTTP/2 Stream Reset O(N^2) Complexity Denial of Service

Denial of Service

Proof Of Concept

No public PoC currently indexed for CVE-2021-32778.

CWE Category CWE-834
Published Date Aug 24, 2021
Modified Date Nov 21, 2024
Exploit Status Not Found
Score 5.8 CVSS v3.1
Exploit Probability (EPSS)
1.23%

Vulnerability Summary

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.

Impacted Vendors

E
enphase 1
E
envoyproxy 1

Reference Links

https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.8
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
CVSS v3.1
Source Entity [email protected]
Severity HIGH
7.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v2.0
Source Entity [email protected]
Severity MEDIUM
5.0
Access Vector
N/A
Authentication
N/A
RAW VECTOR AV:N/AC:L/Au:N/C:N/I:N/A:P

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2021-32778 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data or affected products updated.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

Affected Stack

No specific products linked.