CVE-2019-12523

Se detectó un problema en Squid versiones anteriores a 4.9. Cuando se maneja una petición URN, es realizada una petición HTTP correspondiente. Esta petición HTTP no pasa por las comprobaciones de acceso por las que pasan las peticiones HTTP entrantes. Esto causa que se omitan todas las comprobaciones de acceso y permite el acceso a servidores HTTP restringidos, por ejemplo, un atacante puede conectar con servidores HTTP que solo escuchan en localhost.

USN-4446-1 fixed vulnerabilities in Squid. The update introduced a regression when using Squid with the icap or ecap protocols. This update fixes the problem. Jeriko One discovered that Squid incorrectly handled caching certain requests. A remote attacker could possibly use this issue to perform cache-injection attacks or gain access to reverse proxy features such as ESI. Jeriko One and Kristoffer Danielsson discovered that Squid incorrectly handled certain URN requests. A remote attacker could possibly use this issue to bypass access checks. Jeriko One discovered that Squid incorrectly handled URL decoding. A remote attacker could possibly use this issue to bypass certain rule checks. Jeriko One and Kristoffer Danielsson discovered that Squid incorrectly handled input validation. A remote attacker could use this issue to cause Squid to crash, resulting in a denial of service. Various other issues were also addressed.