PSIRT Advisory

CVE-2004-0230 Blind Reset Attack Using the RST/SYN Bit


TCP stacks that lack RFC 5961 3.2 & 4.2 support (or have it disabled at application level) may allow remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP RST or SYN packet.


Denial of Service (DoS)

Affected Products

FortiAnalyzer 6.2.3 and below

FortiManager 6.2.3 and below


Upgrade to FortiAnalyzer 6.2.4 or above

Upgrade to FortiManager 6.2.4 or above


Restrict hosts that can connect to the GUI to trusted ones only, with the trusted host feature.


  • The following issues reported by vulnerability scanners are directly linked to this issue:

  • "TCP Sequence Number Approximation Based Denial of Service"

  • "Blind Reset Attack Using the RST/SYN Bit"