Heap overflow?

[DJF5]

Hello,

I seem to have the same problem as the person in the link below
[RCU] canary mismatch on erealloc() - heap overflow detected

[Wed Apr 22 10:20:23 2009] [error] ALERT - canary mismatch on erealloc() - heap overflow detected (attacker 'xxx.xxx.xxx.xxx', file '/webroot/roundcube/public/program/lib/PEAR.php', line 275)

I am also running FreeBSD but with Apache1.3 and PHP5.2.8.

I also seem to have 7 httpd-processes 'hanging' in Gracefully finishing. and slurping up 1.00 CPU per process... I am now running at 7.00 full... After a restart of the webserver they are gone ofcourse. But after a day or two there are new hanging processes in the list
There are 7 entries of the given error message in my log file.

[EDIT

The processes that are hanging are without any information

Srv   PID           Acc   M   CPU    SS           Req   Conn   Child   Slot   Client   VHost   Request
5-1   74353   0/0/0   G    0.00   485853   0   0.0   0.00   0.00       (unavailable)
8-1   47987   0/0/0   G    0.00   249475   0   0.0   0.00   0.00       (unavailable)   
9-1   95315   0/0/0   G    0.00   177033   0   0.0   0.00   0.00       (unavailable)   
15-1   53126   0/0/0   G    0.00   92034   0   0.0   0.00   0.00       (unavailable)
24-1   611           0/0/0   G    0.00   176808   0   0.0   0.00   0.00       (unavailable)   
29-1   14229   0/0/0   G    0.00   134593   0   0.0   0.00   0.00       (unavailable)   
30-1   64237   0/0/0   G    0.00   50657   0   0.0   0.00   0.00       (unavailable)


EDIT]

This must be roundcube related as that's the only script i have running on that server.

Is there any info on this issue i can use to solve it?
Is this a known bug?

Any info i can use to make progress on this issue would be greatly appreciated!