CVE-2021-22945

Cuando se envían datos a un servidor MQTT, libcurl versiones anteriores a 7.73.0, incluyéndola y 7.78.0, podría en algunas circunstancias, mantener erróneamente un puntero a un área de memoria ya liberada y usarlo de nuevo en una llamada posterior para enviar datos y también liberarlo *de nuevo*

USN-5079-1 fixed vulnerabilities in curl. One of the fixes introduced a regression on Ubuntu 18.04 LTS. This update fixes the problem. It was discovered that curl incorrect handled memory when sending data to an MQTT server. A remote attacker could use this issue to cause curl to crash, resulting in a denial of service, or possibly execute arbitrary code. Patrick Monnerat discovered that curl incorrectly handled upgrades to TLS. When receiving certain responses from servers, curl would continue without TLS even when the option to require a successful upgrade to TLS was specified. Patrick Monnerat discovered that curl incorrectly handled responses received before STARTTLS. A remote attacker could possibly use this issue to inject responses and intercept communications. Various other issues were also addressed.