Sergio Alvarez has reported a vulnerability in avast!, which can be exploited by malicious people to compromise a vulnerable system.
The vulnerability is caused due to an error within the parsing of .CAB files and can be exploited to cause a heap-based buffer overflow via a specially crafted .CAB file.
Successful exploitation may allow execution of arbitrary code.
The vulnerability reportedly affects versions prior to 4.7.766 for servers and 4.7.700 for the Managed Client product.
Update to the latest versions.