FreeBSD VuXML: Documenting security issues in FreeBSD and the FreeBSD Ports Collection

FreeBSD -- Resource exhaustion in TCP reassembly

Affected packages
11.2 <= FreeBSD-kernel < 11.2_1
11.1 <= FreeBSD-kernel < 11.1_12
10.4 <= FreeBSD-kernel < 10.4_10


VuXML ID 3c2eea8c-99bf-11e8-8bee-a4badb2f4699
Discovery 2018-08-06
Entry 2018-08-06

Problem Description:

One of the data structures that holds TCP segments uses an inefficient algorithm to reassemble the data. This causes the CPU time spent on segment processing to grow linearly with the number of segments in the reassembly queue.


An attacker who has the ability to send TCP traffic to a victim system can degrade the victim system's network performance and/or consume excessive CPU by exploiting the inefficiency of TCP reassembly handling, with relatively small bandwidth cost.


CVE Name CVE-2018-6922
FreeBSD Advisory SA-18:08.tcp