Vulnerability Name:

CVE-2021-32778 (CCN-208236)

Assigned:2021-08-24
Published:2021-08-24
Updated:2022-06-15
Summary: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.
CVSS v3 Severity:7.5 High (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
6.5 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): High
5.8 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L)
5.1 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Low
CVSS v2 Severity:5.0 Medium (CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Authentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
5.0 Medium (CCN CVSS v2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Low
Athentication (Au): None
Impact Metrics:Confidentiality (C): None
Integrity (I): None
Availibility (A): Partial
Vulnerability Type:CWE-834
Vulnerability Consequences:Denial of Service
References:Source: MITRE
Type: CNA
CVE-2021-32778

Source: XF
Type: UNKNOWN
envoy-cve202132778-dos(208236)

Source: CCN
Type: Envoy GIT Repository
Excessive CPU utilization when closing HTTP/2 streams

Source: CONFIRM
Type: Third Party Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc

Source: MISC
Type: Release Notes, Vendor Advisory
https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history

Source: CCN
Type: WhiteSource Vulnerability Database
CVE-2021-32778

Vulnerable Configuration:Configuration 1:
  • cpe:/a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*
  • OR cpe:/a:envoyproxy:envoy:*:*:*:*:*:*:*:* (Version >= 1.16.0 and < 1.16.5)
  • OR cpe:/a:envoyproxy:envoy:*:*:*:*:*:*:*:* (Version >= 1.17.0 and < 1.17.4)
  • OR cpe:/a:envoyproxy:envoy:*:*:*:*:*:*:*:* (Version >= 1.18.0 and < 1.18.4)

    • Configuration CCN 1:
  • cpe:/a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*
  • OR cpe:/a:envoyproxy:envoy:1.18.3:*:*:*:*:*:*:*
  • OR cpe:/a:envoyproxy:envoy:1.17.3:*:*:*:*:*:*:*
  • OR cpe:/a:envoyproxy:envoy:1.16.4:*:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    envoyproxy envoy 1.19.0
    envoyproxy envoy *
    envoyproxy envoy *
    envoyproxy envoy *
    envoyproxy envoy 1.19.0
    envoyproxy envoy 1.18.3
    envoyproxy envoy 1.17.3
    envoyproxy envoy 1.16.4