CVE-2014-6053

La función rfbProcessClientNormalMessage en libvncserver/rfbserver.c en LibVNCServer 0.9.9 y anteriores no maneja correctamente los intentos de enviar una cantidad grande de datos ClientCutText, lo que permite a atacantes remotos causar una denegación de servicio (consumo de memoria o caída del demonio) a través de un mensaje manipulado que está procesado mediante el uso de un único malloc no comprobado.

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client.

An integer overflow in liblzo before 2.07 allows attackers to cause a denial of service or possibly code execution in applications using performing LZO decompression on a compressed payload from the attacker. The libvncserver library is built with a bundled copy of minilzo, which is a part of liblzo containing the vulnerable code. A malicious VNC server can trigger incorrect memory management handling by advertising a large screen size parameter to the VNC client. This would result in multiple memory corruptions and could allow remote code execution on the VNC client. A malicious VNC client can trigger multiple DoS conditions on the VNC server by advertising a large screen size, ClientCutText message length and/or a zero scaling factor parameter. A malicious VNC client can trigger multiple stack-based buffer overflows by passing a long file and directory names and/or attributes when using the file transfer message feature.