CVE-2017-7521

Las versiones de OpenVPN anteriores a 2.4.3 y 2.3.17, son vulnerables a una denegación de servicio remota debido a un agotamiento de memoria causado por pérdida de memoria y un problema de doble liberación (Double Free) en la función extract_x509_extension().

Karthikeyan Bhargavan and Gaetan Leurent discovered that 64-bit block ciphers are vulnerable to a birthday attack. A remote attacker could possibly use this issue to recover cleartext data. Fixing this issue requires a configuration change to switch to a different cipher. This update adds a warning to the log file when a 64-bit block cipher is in use. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. It was discovered that OpenVPN incorrectly handled rollover of packet ids. An authenticated remote attacker could use this issue to cause OpenVPN to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 16.10. Various other issues were also addressed.