Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2021-32778

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
24/08/2021
Last modified:
15/06/2022

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
7.50
Severity 3.x
HIGH
Vector 2.0
AV:N/AC:L/Au:N/C:N/I:N/A:P CVSS v2.0 Severity and Metrics:

Base Score: 5.00 MEDIUM
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P

Attack Vector (AV): Network
Attack Complexity (AC): Low
Authentication (Au): None
Confidentiality (C): None
Integrity (I): None
Availability (A): Physical

Base Score 2.0
5.00
Severity 2.0
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* 1.16.0 (including) 1.16.5 (excluding)
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* 1.17.0 (including) 1.17.4 (excluding)
cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* 1.18.0 (including) 1.18.4 (excluding)
cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools