ValueError when running savupdate in Debian8

Hello,

I've installed Sophos AntiVirus (Free edition) on my private server running Debian 8. Unfortunately I can't fetch any updates, 'savupdate' always raised the following error message:

# ./bin/savupdate
Automatic update aborted
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "Updater.py", line 756, in main
  File "Updater.py", line 724, in tryRun
  File "Updater.py", line 663, in run
  File "Updater.py", line 386, in doUpdateAndRecordResult
  File "Updater.py", line 158, in tryUpdate
  File "Updater.py", line 129, in update
  File "SddsUpdater.py", line 816, in update
  File "targetsystem.py", line 776, in checkIfUpdatableToSLS
  File "targetsystem.py", line 760, in checkKernelVersionForSLS
  File "targetsystem.py", line 646, in kernelVersionIsAtLeast
  File "targetsystem.py", line 624, in versionCompare
ValueError: invalid literal for int() with base 10: 'stk32'

This issue seems to come from the kernel version, which is running on this vServer. The output of uname is:

# uname -a
Linux rdm 3.2.64.stk32 #2 SMP Tue Nov 18 14:54:13 UTC 2014 x86_64 GNU/Linux

Is there any possibility to get updates? As this is a vServer, I can't change the kernel version unfortunately.

Thanks for any hints and recommendations!