CVE-2020-25686

A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

Se encontró un fallo en dnsmasq versiones anteriores a 2.83. Al recibir una consulta, dnsmasq no comprueba si existe una petición pendiente existente para el mismo nombre y reenvía una nueva petición. Por defecto, se puede enviar un máximo de 150 consultas pendientes a los servidores aguas arriba, por lo que puede haber como máximo 150 consultas para el mismo nombre. Este fallo permite a un atacante fuera de ruta en la red reduzca sustancialmente el número de intentos que tendría que realizar para falsificar una respuesta y hacer que dnsmasq la acepte. Este problema se menciona en la sección "Birthday Attacks" de RFC5452. Si se encadenaba con CVE-2020-25684, se reduce la complejidad del ataque de un ataque con éxito. La mayor amenaza de esta vulnerabilidad es la integridad de los datos