CVE-2025-64763
BaseFortify
Publication date: 2025-12-03
Last updated on: 2025-12-05
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| envoyproxy | envoy | to 1.33.13 (exc) |
| envoyproxy | envoy | From 1.34.0 (inc) to 1.34.11 (exc) |
| envoyproxy | envoy | From 1.35.0 (inc) to 1.35.7 (exc) |
| envoyproxy | envoy | From 1.36.0 (inc) to 1.36.3 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-693 | The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability occurs in Envoy when it is configured in TCP proxy mode to handle CONNECT requests. Envoy accepts client data before sending a 2xx success response and forwards that data upstream. If an upstream proxy then responds with a non-2xx status, it can cause a de-synchronized CONNECT tunnel state. This happens because Envoy forwards early data before the connection is fully established, potentially leading to communication issues.
How can this vulnerability impact me? :
The vulnerability can cause a de-synchronized CONNECT tunnel state, which may disrupt communication between clients and upstream servers. This could lead to unexpected behavior or failures in establishing TCP tunnels through Envoy, potentially impacting the reliability of network connections that depend on CONNECT tunnels.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, set the runtime flag envoy.reloadable_features.reject_early_connect_data to reject CONNECT requests that send data before a 2xx response. This prevents Envoy from accepting early client data that could cause a de-synchronized CONNECT tunnel state when upstream proxies reject the connection.