CVE-2021-36740

Varnish Cache, con HTTP/2 habilitado, permite el contrabando de peticiones y la omisión de autorización de VCL por medio de un encabezado Content-Length grande para una petición POST. Esto afecta a Varnish Enterprise versiones 6.0.x anteriores a 6.0.8r3, y Varnish Cache versiones 5.xy 6.x anteriores a 6.5.2, versiones 6.6.x anteriores a 6.6.1 y versiones 6.0 LTS anteriores a 6.0.8

A flaw was found in Varnish. The Varnish Cache, with HTTP/2 enabled, allows request smuggling and VCL authorization bypass via a large Content-Length header for a POST request. As a result, this flaw allows the information on the Varnish cache to be poisoned. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

It was dicovered that Varnish Cache did not clear a pointer between the handling of one client request and the next request within the same connection. A remote attacker could possibly use this issue to obtain sensitive information. It was discovered that Varnish Cache could have an assertion failure when a TLS termination proxy uses PROXY version 2. A remote attacker could possibly use this issue to restart the daemon and cause a performance loss.