Upgrade to version 1.2.6 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.
Vendor URL: http://www.punbb.org/
Vendor Specific News/Changelog Entry: http://www.punbb.org/changelogs/1.2.5_to_1.2.6.txt
Related OSVDB ID: 17986
Related OSVDB ID: 17987