The commit also says "This particularly shows up when slow_start_after_idle is disabled as a dangerous cwnd inflation (1.5 x RTT) after few seconds of idle time

The commit also says "This particularly shows up when slow_start_after_idle is disabled as a dangerous cwnd inflation (1.5 x RTT) after few seconds of idle time." And the slow_start_after_idle sysctl is enabled by default. The bug fix is in the CUBIC congestion control algorithm, which has been the default in Linux TCP since kernel 2.6.19 (released in November 2007). So impact in distros has been ~ 2008-2015.