Linux kernel - challenge ack information leak

Summary

net/ipv4/tcp_input.c in certain Linux kernel versions does not properly determine the rate of challenge ACK segments, which makes it easier for remote attackers to hijack TCP sessions via a blind in-window attack.

Affected Products

FortiOS versions
<ul>
<li>5.2.8 and below</li>
<li>5.4.0 & 5.4.1</li>
</ul>
FortiAnalyzer versions 5.4.0 & 5.4.1

Solutions

For FortiOS, upgrade to versions
5.2.9 or
5.4.2 or
5.6.0 or
5.4.2 or
upcoming 5.6.0

References

• https://nvd.nist.gov/vuln/detail/CVE-2016-5696