It is possible.
I know people to have uploaded a .GIF image file and instructing people to download it and rename it *.JS - upon running the .JS file, the computer is basically buggered.
Rich::
1 2008-08-31 21:30
Re: Can an Image Placed on a Forum Contain a Virus? (4 replies, posted in PunBB 1.2 discussion)
2 2008-08-26 11:35
Re: Profile avatar page visual glitch (5 replies, posted in PunBB 1.3 troubleshooting)
Worked like a charm! Thankyou!
Rich::
3 2008-08-25 15:23
Re: Profile avatar page visual glitch (5 replies, posted in PunBB 1.3 troubleshooting)
Slavok wrote:
Thank you for having initiated the topic. You have just reminded us to release a hotfix for this bug.
You will see a notification about new hotfixes available at the top of every page in the administration mode.
Hotfixes are installed in the same way as extensions on the following page: <FORUM_URL>/admin/extensions.php?section=install
Is this hotfix available yet? It's not showing up on my install 
Rich::
4 2008-08-23 23:21
Topic: Profile avatar page visual glitch (5 replies, posted in PunBB 1.3 troubleshooting)
Not sure where to post this, so I posted it here.
On the profile page, avatar selection section, there is the text at the very top of the page:
Notice: Undefined index: Avatar info change in /home/spiritus/public_html/profile.php on line 2166
It is not a critical bug, merely visual but annoying nonetheless.
I tried erasing the database, reinstalling from scratch, re-uploading the files etc, no avail.
One other little bug on the page - the avatar is misplaced slightly.
Otherwise, PunBB 1.3 kicks ***!
[EDIT] Just checked it on these boards, the problem is here too, so you probably know all about it!
Rich::