Header injection vulnerability in Apache APISIX.

The attacker can take advantage of certain configuration in forward-auth plugin to inject malicious headers. This issue affects Apache APISIX: from 2.12.0 through 3.15.0.

Users are recommended to upgrade to version 3.16.0, which fixes the issue.

In Apache APISIX before 2.13.0, when decoding JSON with duplicate keys, lua-cjson will choose the last occurred value as the result. By passing a JSON with a duplicate key, the attacker can bypass the bodyschema validation in the request-validation plugin. For example, {"stringpayload":"bad","stringpayload":"good"} can be used to hide the "bad" input. Systems satisfy three conditions below are affected by this attack: 1. use bodyschema validation in the request-validation plugin 2. upstream application uses a special JSON library that chooses the first occurred value, like jsoniter or gojay 3. upstream application does not validate the input anymore. The fix in APISIX is to re-encode the validated JSON input back into the request body at the side of APISIX. Improper Input Validation vulnerability in COMPONENT of Apache APISIX allows an attacker to IMPACT. This issue affects Apache APISIX Apache APISIX version 2.12.1 and prior versions.

An attacker can abuse the batch-requests plugin to send requests to bypass the IP restriction of Admin API. A default configuration of Apache APISIX (with default API key) is vulnerable to remote code execution. When the admin key was changed or the port of Admin API was changed to a port different from the data panel, the impact is lower. But there is still a risk to bypass the IP restriction of Apache APISIX's data panel. There is a check in the batch-requests plugin which overrides the client IP with its real remote IP. But due to a bug in the code, this check can be bypassed.