As of May 6, four out of five vendors have provided NSS Labs with fixes for the TCP Split Handshake issue

May 12, 2011

2 Min Read


CARLSBAD, Calif., May 10, 2011 - NSS Labs, Inc., the leading independent security testing organization, today announced that several vendors have released updates to their products to address the TCP Split Handshake issues. The TCP issue was one of many tests in the Network Firewall Comparative Group Test Report released on April 12. Known for its rigorous testing that mimics the efforts of modern cyber criminals, NSS Labs engineers discovered serious flaws in five of six network firewalls, despite the maturity of the market and their certification by two other major certification bodies. NSS Labs performed this testing independently with no vendor funding. Affected vendors were notified of the issue in early February. As of May 6, four out of five vendors have provided NSS Labs with fixes for the TCP Split Handshake issue, which NSS Labs has been able to test and validate in our lab: - Fortinet delivered a patch to their firewall. - Juniper changed the default setting to enable protection. - Palo Alto Networks delivered a patch to their firewall. - SonicWALL delivered a patch to their firewall. - Cisco has not issued a patch, but recommends a workaround using access control lists (ACLs), which provides protection in some but not all cases. Enabling this protection may have a negative impact on performance and/or break applications that are not using TCP properly. NSS Labs recommends enterprises test the configuration prior to deployment in order to ascertain the impact. “NSS Labs commends the vendors who have taken steps to deliver protection for their customers,” said Vik Phatak, CTO, NSS Labs. “End-user organizations need rigorous independent testing to help them identify and remediate gaps in their network and systems security.” The Network Firewall Comparative Group Test Report, along with updated remediation guidance, is currently available to NSS Labs’ subscribers at: About NSS Labs, Inc. NSS Labs, Inc. is the leading independent, information security research and testing organization. Its expert analyses provide information technology professionals with the unbiased data they need to select and maintain complex security products for their organizations. Pioneering intrusion detection and prevention system testing with the publication of the first such test criteria in 1999, NSS Labs evaluates firewall, unified threat management, anti-malware, encryption, web application firewall, and other technologies on a regular basis. The firm’s real-world test methodology is the only one to assess security products against live Internet threats. NSS Labs tests are considered the most aggressive in the industry. Founded in 1991, the company has offices in Carlsbad, California and Austin, Texas. For more information, visit

Keep up with the latest cybersecurity threats, newly discovered vulnerabilities, data breach information, and emerging trends. Delivered daily or weekly right to your email inbox.

You May Also Like

More Insights