AVI WAF mitigation for CVE-2025-29891

Products

• VMware Avi Load Balancer

Issue/Introduction

AVI itself is not vulnerable, this is a mitigation for backend servers that are being load balanced through AVI that can be affected by CVE-2025-27636 which can affect Apache Tomcat servers that are in versions lower than:

4.10.2 for 4.10.x LTS

4.8.5 for 4.8.x LTS

3.22.4 for 3.x releases

Cause

Security advisory from CVE-2025-29891

 

Bypass/Injection vulnerability in Apache Camel components under particular conditions. This issue affects Apache Camel: from 4.10.0 through <= 4.10.1, from 4.8.0 through <= 4.8.4, from 3.10.0 through <= 3.22.3. Users are recommended to upgrade to version 4.10.2 for 4.10.x LTS, 4.8.5 for 4.8.x LTS and 3.22.4 for 3.x releases. This vulnerability is present in Camel's default incoming header filter, that allows an attacker to include Camel specific headers that for some Camel components can alter the behaviours such as the camel-bean component, to call another method on the bean, than was coded in the application. In the camel-jms component, then a mallicous header can be used to send the message to another queue (on the same broker) than was coded in the application. The attacker would need to inject custom headers, such as HTTP protocols. So if you have Camel applications that are directly connected to the internet via HTTP, then an attacker could include malicious HTTP headers in the HTTP requests that are send to the Camel application. All the known Camel HTTP component such as camel-servlet, camel-jetty, camel-undertow, camel-platform-http, and camel-netty-http would be vulnerable out of the box. In these conditions an attacker could be able to forge a Camel header name and make the bean component invoking other methods in the same bean. In terms of usage of the default header filter strategy the list of components using that is: * camel-activemq * camel-activemq6 * camel-amqp * camel-aws2-sqs * camel-azure-servicebus * camel-cxf-rest * camel-cxf-soap * camel-http * camel-jetty * camel-jms * camel-kafka * camel-knative * camel-mail * camel-nats * camel-netty-http * camel-platform-http * camel-rest * camel-sjms * camel-spring-rabbitmq * camel-stomp * camel-tahu * camel-undertow * camel-xmpp The vulnerability arises due to a bug in the default filtering mechanism that only blocks headers starting with "Camel", "camel", or "org.apache.camel.".  Mitigation: You can easily work around this in your Camel applications by removing the headers in your Camel routes. There are many ways of doing this, also globally or per route. This means you could use the removeHeaders EIP, to filter out anything like "cAmel, cAMEL" etc, or in general everything not starting with "Camel", "camel" or "org.apache.camel.".

Resolution

To mitigate this issue from the AVI side we can use WAF pre CSR Rules, for this follow this path:

Templates>WAF>WAF Policy edit the WAF Policy that you're using:

Go to the signatures tab of this configuration and look for Pre-CRS Groups and click on add:

 

Enter a name to identify this Pre CSR group and then click on add to add the rule itself:

 

Enter a name for the rule, select enforcement and enter the following inside the Rule itself:

SecRule ARGS_NAMES|REQUEST_HEADERS_NAMES "@rx ^(?!(Camel|camel|org\.apache\.camel\.))([Cc][Aa][Mm][Ee][Ll]|[Oo][Rr][Gg]\.[Aa][Pp][Aa][Cc][Hh][Ee]\.[Ca][Aa][Mm][Ee][Ll]\.)." "id:4099860,phase:2,block,t:none,msg:'CVE-2025-27636, CVE-2025-29891'"

Save the configuration until finished

Additional Information

Note:  it is strongly advised to upgrade the Apache Tomcat servers to one of the fixed versions to fully mitigate this CVE