Neel Metha of Internet Security Systems' (ISS) X-Force discovered a buffer overflow vulnerability in Snort, which according to ISS also affects Sourcefire--the commercial version of Snort. The vulnerability exists in the Back Orifice pre-processor and can be exploited with a single UDP packet. Such a packet could be sent directly to a system running Snort or Sourcefire. Because the tools can also inspect all traffic passing into a network an exploit might also be possible by sending a special UDP packet into a network protected by the tools.
Systems that do not use the Back Orifice pre-processor are not affected. Snort 2.4.3 was released to correct the problem. For more details about the problem in Snort read the announcement on the Snort.org Web site and ISS' advisory . At the time of this writing no information was available about updates to Sourcefire.