After several extensive internal and external security audits which discovered 22 distinct vulnerabilities, we are releasing Gallery 3.0.4 as a security release. All of the issues require that someone with malicious intent either have an account with edit permissions, or trick a user with edit permissions into clicking on a malicious link. In most cases, this can only lead to a possible XSS vulnerability, but in several instances it allows arbitrary PHP code execution.
We thank the following individuals for reporting these issues: Chalk, Mateusz Goik, James 'albino' Kettle, Emanuel Bronshtein, and Sergey Markov. Due to their efforts, they will each be receiving bounties of $1000 for their help in making Gallery more secure.
http://gallery.menalto.com/gallery_3_0_4
http://downloads.sourceforge.net/gallery/gallery-3.0.4.zip