CVE-2021-28543

Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers.

Varnish varnish-modules before 0.17.1 allows remote attackers to cause a denial of service (daemon restart) in some configurations. This does not affect organizations that only install the Varnish Cache product; however, it is common to install both Varnish Cache and varnish-modules. Specifically, an assertion failure or NULL pointer dereference can be triggered in Varnish Cache through the varnish-modules header.append() and header.copy() functions. For some Varnish Configuration Language (VCL) files, this gives remote clients an opportunity to cause a Varnish Cache restart. A restart reduces overall availability and performance due to an increased number of cache misses, and may cause higher load on backend servers.

Varnish varnish-modules versiones anteriores a 0.17.1, permite a atacantes remotos causar una denegación de servicio (reinicio del demonio) en algunas configuraciones. Esto no afecta a organizaciones que solo instalan el producto Varnish Cache; sin embargo, es común instalar tanto Varnish Cache como varnish-modules. Específicamente, un error de aserción o desreferencia del puntero NULL se puede activar en Varnish Cache por medio de las funciones header.append() y header.copy() de varnish-modules. Para algunos archivos de Varnish Configuration Language (VCL), esto brinda a clientes remotos la oportunidad de causar un reinicio de Varnish Cache. Un reinicio reduce la disponibilidad y el rendimiento general debido a un mayor número de pérdidas de caché y puede causar una mayor carga en los servidores de backend