7.5
CVSSv3

CVE-2021-32780

Published: 24/08/2021 Updated: 15/06/2022
CVSS v2 Base Score: 5 | Impact Score: 2.9 | Exploitability Score: 10
CVSS v3 Base Score: 7.5 | Impact Score: 3.6 | Exploitability Score: 3.9
VMScore: 445
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P

Vulnerability Summary

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions Envoy transitions a H/2 connection to the CLOSED state when it receives a GOAWAY frame without any streams outstanding. The connection state is transitioned to DRAINING when it receives a SETTING frame with the SETTINGS_MAX_CONCURRENT_STREAMS parameter set to 0. Receiving these two frames in the same I/O event results in abnormal termination of the Envoy process due to invalid state transition from CLOSED to DRAINING. A sequence of H/2 frames delivered by an untrusted upstream server will result in Denial of Service in the presence of untrusted **upstream** servers. Envoy versions 1.19.1, 1.18.4 contain fixes to stop processing of pending H/2 frames after connection transition to the CLOSED state.

Vulnerability Trend

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envoyproxy envoy 1.19.0

envoyproxy envoy

Vendor Advisories

Envoy, as used by Istio before version 1111, contains a remotely exploitable vulnerability where an untrusted upstream service could cause Envoy to terminate abnormally by sending the GOAWAY frame followed by the SETTINGS frame with the SETTINGS_MAX_CONCURRENT_STREAMS parameter set to 0 ...