From RHSA Announce:
[RHSA-2011:0259-01] Critical: flash-plugin - 1-Month End Of Life Notice
The flash-plugin package on Red Hat Enterprise Linux 4 contains multiple security flaws and should no longer be used. This is the 1-month notification of Red Hat's plans to disable Adobe Flash Player 9 on Red Hat Enterprise Linux 4.
The Red Hat Security Response Team has rated this update as having critical security impact.
Adobe's security caveats apply to Linux as well as Windows.
regards,
benm