Secunia has posted a vulnerability marked as "highly critical" for users of any of the Avaya products that use PHP:

Avaya has acknowledged some vulnerabilities in various Avaya products, where some have unknown impacts and others can be exploited by malicious users to bypass certain security restrictions and potentially by malicious people to compromise a vulnerable system.

The following products are affected:

• Avaya Communication Manager (CM 4.0 and CM 2.x prior to load 127.0)
• Avaya CCS/SES (CCS/SES 3.1.1)
• Avaya AES (AES 4.0)

Currently, according to the original announcement from Avaya, there are two issues that have been found and are able to be exploited - an issue with the xmlrpc extension and a problem with the ftp extension. Currently, there is no patch to correct these issues, but you can keep track of their current status via their entries