CVE-2021-32780 Incorrect handling of H/2 GOAWAY followed by SETTINGS frames
An attacker controlling an upstream server can cause Envoy to crash by sending specific HTTP/2 frames, resulting in a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-32780?
CVE-2021-32780 is a high-severity denial of service vulnerability in Envoyproxy Envoy, published on 24 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-754
Which versions are affected by CVE-2021-32780?
1 open source package ship an affected version, including envoy. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
envoy Bitnami | From 1.18.0 | 1.18.4, 1.19.1 |
Products include Envoyproxy Envoy.
How do I fix CVE-2021-32780?
Upgrade envoy to a fixed version for your release line: 1.18.4 or 1.19.1.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-32780 being exploited?
There is no known exploitation of CVE-2021-32780 in the wild and no public exploit code.
Other vulnerabilities in Envoyproxy Envoy
Sources
Also known as BIT-envoy-2021-32780, GHSA-j374-mjrw-vvp8.