CVE-2023-27496: Envoy may crash when a redirect url without a state param is received in the oauth filter
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, the OAuth filter assumes that a state query param is present on any response that looks like an OAuth redirect response. Sending it a request with the URI path equivalent to the redirect path, without the state parameter, will lead to abnormal termination of Envoy process. Versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9 contain a patch. The issue can also be mitigated by locking down OAuth traffic, disabling the filter, or by filtering traffic before it reaches the OAuth filter (e.g. via a lua script).
Other sources
If Envoy is running with the OAuth filter enabled exposed, a malicious actor could construct a request which would cause denial of service by crashing Envoy.
— Red Hat
Affected Software
Event History
Frequently Asked Questions
What is CVE-2023-27496?
CVE-2023-27496 is a vulnerability in Envoy, an open-source edge and service proxy, that allows an attacker to bypass OAuth security measures.
What is the severity of CVE-2023-27496?
CVE-2023-27496 has a severity value of 7.5, which is considered high.
How does CVE-2023-27496 affect Envoy?
CVE-2023-27496 affects Envoy versions 1.22.9, 1.23.0 to 1.23.6, 1.24.0 to 1.24.4, and 1.25.0 to 1.25.3 by assuming the presence of a `state` query parameter on OAuth redirect responses.
How can an attacker exploit CVE-2023-27496?
An attacker can exploit CVE-2023-27496 by sending a request without the expected `state` query parameter to bypass OAuth security measures.
How can I mitigate CVE-2023-27496?
To mitigate CVE-2023-27496, upgrade Envoy to version 1.22.9, 1.23.6, 1.24.4, 1.25.3, or newer.