CVE-2024-24814: Denial of service when manipulating mod_auth_openidc_session_chunks cookie in mod_auth_openidc

modauthopenidc is an OpenID Certified™ authentication and authorization module for the Apache 2.x HTTP server that implements the OpenID Connect Relying Party functionality. In affected versions missing input validation on modauthopenidcsessionchunks cookie value makes the server vulnerable to a denial of service (DoS) attack. An internal security audit has been conducted and the reviewers found that if they manipulated the value of the modauthopenidcsessionchunks cookie to a very large integer, like 99999999, the server struggles with the request for a long time and finally gets back with a 500 error. Making a few requests of this kind caused our server to become unresponsive. Attackers can craft requests that would make the server work very hard (and possibly become unresponsive) and/or crash with minimal effort. This issue has been addressed in version 2.4.15.2. Users are advised to upgrade. There are no known workarounds for this vulnerability.