PT-2021-19926 · Envoy · Envoy
Chaoqin Li
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Published
2021-08-24
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Updated
2024-03-06
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CVE-2021-32780
CVSS v3.1
8.6
High
| Vector | AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
Name of the Vulnerable Software and Affected Versions
Envoy versions prior to 1.18.4
Envoy versions prior to 1.19.1
Description
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.Recommendations
For versions prior to 1.18.4, update to version 1.18.4 or later to stop processing of pending H/2 frames after connection transition to the CLOSED state.
For versions prior to 1.19.1, update to version 1.19.1 or later to stop processing of pending H/2 frames after connection transition to the CLOSED state.
As a temporary workaround, consider restricting access to untrusted upstream servers to minimize the risk of exploitation.
Fix
DoS
Improper Check for Exceptional Conditions
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Weakness Enumeration
Related Identifiers
Affected Products
Envoy