Call for information: Unknow bug in EntLib 4.1 (caching block)?

Topics: Caching Application Block
Apr 11, 2013 at 8:07 AM
Edited Apr 11, 2013 at 9:35 AM
Altinn is the Norwegian public reporting portal. This is a portal where Norwegians can among other things "do their taxes". The portal has been known for breaking down each year when all the Norwegians login at the same time to check if they get money in return or need to pay more tax.

This year an issue occured where some users got to see another user's data. They fixed the issue and later released a statement claiming the problem was an unknown bug in Enterprise Library 4.1. I assume it was in the caching block, but details were scarse. Also they say the problem is fixed in 5.0, but neither fixed nor listed as an issue in 4.1

Now to my question. Anyone know any more details about this issue? We are using the 4.1 caching block in a large project. Migrating to 5.0 is not planned for now and I'd like to know if this unknown bug can affect us and if it's patchable.

Update: I now know that the bug was in the Data Access Application Block, but not what the fault is.

Source:
http://www.digi.no/914815/microsoft-bibliotek-sviktet-altinn

Google translated:
http://translate.google.no/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&eotf=1&u=http%3A%2F%2Fwww.digi.no%2F914815%2Fmicrosoft-bibliotek-sviktet-altinn&act=url