CVE-2021-32778: medium-severity vulnerability in envoyproxy envoy
Excessive CPU utilization when closing HTTP/2 streams
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.8epss 1.2%
exploitation probability
1.2%top 32% of all CVEs
observed exploitation
nono source reports it
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:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
Affected products
envoyproxy · envoyRelated CVEs — envoyproxy envoy
In the same product, most dangerous first.
CVE-2024-30255MEDIUMHTTP/2: CPU exhaustion due to CONTINUATION frame floodEPSS 87.8%CVE-2024-27919HIGHHTTP/2: memory exhaustion due to CONTINUATION frame floodEPSS 86.7%CVE-2021-29492HIGHBypass of path matching rules using escaped slash charactersEPSS 66.2%CVE-2021-32777HIGHIncorrect concatenation of multiple value request headers in ext-authz extensionEPSS 3.3%CVE-2021-21378HIGHJWT authentication bypass with unknown issuer tokenEPSS 1.7%CVE-2022-29225HIGHZip bomb vulnerability in EnvoyEPSS 1.6%