Dragonfly through 2.0.2 contains an unbounded memory allocation vulnerability that allows unauthenticated clients to exhaust memory by passing a negative COUNT to HRANDFIELD, ZRANDMEMBER or SRANDMEMBER. Attackers can send a single command against a one-element key with a huge negative COUNT to trigger the OOM killer, terminating the instance for all clients.
The securelevels implementation in FreeBSD 7.0 and earlier, OpenBSD up to 3.8, DragonFly up to 1.2, and Linux up to 2.6.15 allows root users to bypass immutable settings for files by mounting another filesystem that masks the immutable files while the system is running.