A flaw in the processing of received ICMP errors (ICMP fragment needed and
ICMP redirect) in the Linux kernel functionality was found to allow the
ability to quickly scan open UDP ports. This flaw allows an off-path remote
user to effectively bypass the source port UDP randomization. The highest
threat from this vulnerability is to confidentiality and possibly
integrity, because software that relies on UDP source port randomization
are indirectly affected as well.

Keyu Man discovered that the ICMP implementation in the Linux kernel did
not properly handle received ICMP error packets. A remote attacker could
use this to facilitate attacks on UDP based services that depend on source
port randomization.