CVE-2021-32780

Name: CVE-2021-32780
Creator: NVD / NIST
Published: 2021-08-24T21:15:09.947+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.23%

Last modified Jun 17, 2026

CVE-2021-32780 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 1.23% chance of exploitation in the next 30 days.

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. 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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.23%

65.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Envoyproxy	Envoy	>= 1.18.0, < 1.18.4
Envoyproxy	Envoy	1.19.0

References

https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8Third Party Advisory
https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyVendor Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-j374-mjrw-vvp8Third Party Advisory
https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyVendor Advisory

Timeline

Published: Aug 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-32780?

How severe is CVE-2021-32780?

CVE-2021-32780 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.23% probability of exploitation in the next 30 days.

How do I fix CVE-2021-32780?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-32780?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST