CVE-2021-32780: Incorrect handling of H/2 GOAWAY followed by SETTINGS frames
First published: Tue Aug 24 2021(Updated: )
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.
Credit: security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Envoyproxy Envoy | >=1.18.0<1.18.4 | |
| Envoyproxy Envoy | =1.19.0 |
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Reference Links
Frequently Asked Questions
What is CVE-2021-32780?
CVE-2021-32780 is a vulnerability in Envoy, an open-source L7 proxy and communication bus, where a H/2 connection is transitioned to the CLOSED state when it receives a GOAWAY frame without any streams outstanding, leading to potential denial of service.
How does CVE-2021-32780 affect Envoy?
In affected versions of Envoy (1.18.0 to 1.18.4, and 1.19.0), a H/2 connection is transitioned to the CLOSED state when it receives a GOAWAY frame without any streams outstanding, potentially causing denial of service.
What is the severity of CVE-2021-32780?
CVE-2021-32780 has a severity rating of 7.5 (high).
How do I fix CVE-2021-32780?
To fix CVE-2021-32780, it is recommended to upgrade to the latest version of Envoy (1.18.5 or 1.19.1) where the vulnerability is patched.
Where can I find more information about CVE-2021-32780?
You can find more information about CVE-2021-32780 on the Envoy security advisory page (https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8) and the Envoy documentation (https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history).
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