CVE-2022-2053

/// Technical description

When a POST request comes through AJP and the request exceeds the max-post-size limit (maxEntitySize), Undertow's AjpServerRequestConduit implementation closes a connection without sending any response to the client/proxy. This behavior results in that a front-end proxy marking the backend worker (application server) as an error state and not forward requests to the worker for a while. In mod_cluster, this continues until the next STATUS request (10 seconds intervals) from the application server updates the server state. So, in the worst case, it can result in "All workers are in error state" and mod_cluster responds "503 Service Unavailable" for a while (up to 10 seconds). In mod_proxy_balancer, it does not forward requests to the worker until the "retry" timeout passes. However, luckily, mod_proxy_balancer has "forcerecovery" setting (On by default; this parameter can force the immediate recovery of all workers without considering the retry parameter of the workers if all workers of

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References