Bugzilla 2.19.3 through 2.20 does not properly handle "//" sequences in URLs when redirecting a user from the login form, which could cause it to generate a partial URL in a form action that causes the user's browser to send the form data to another domain.

Bugzilla 2.16.10, 2.17 through 2.18.4, and 2.20 does not properly handle certain characters in the mostfreqthreshold parameter in duplicates.cgi, which allows remote attackers to trigger a SQL error.

Bugzilla 2.16.10 does not properly handle certain characters in the (1) maxpatchsize and (2) maxattachmentsize parameters in attachment.cgi, which allows remote attackers to trigger a SQL error.

SQL injection vulnerability in whineatnews.pl in Bugzilla 2.17 through 2.18.4 and 2.20 allows remote authenticated users with administrative privileges to execute arbitrary SQL commands via the whinedays parameter, as accessible from editparams.cgi.

The shadow database feature (syncshadowdb) in Bugzilla 2.9 through 2.16.10 allows local users to overwrite arbitrary files via a symlink attack on temporary files.

Bugzilla 2.18rc1 through 2.18.3, 2.19 through 2.20rc2, and 2.21 allows remote attackers to obtain sensitive information such as the list of installed products via the config.cgi file, which is accessible even when the requirelogin parameter is set.

Bugzilla 2.19.1 through 2.20rc2 and 2.21, with user matching turned on in substring mode, allows attackers to list all users whose names match an arbitrary substring, even when the usevisibilitygroups parameter is set.

Bugzilla 2.17.x, 2.18 before 2.18.2, 2.19.x, and 2.20 before 2.20rc1 inserts a bug into the database before it is marked private, which introduces a race condition and allows attackers to access information about the bug via buglist.cgi before MySQL replication is complete.

The Flag::validate and Flag::modify functions in Bugzilla 2.17.1 to 2.18.1 and 2.19.1 to 2.19.3 do not verify that the flag ID is appropriate for the given bug or attachment ID, which allows users to change flags on arbitrary bugs and obtain a bug summary via process_bug.cgi.

Bugzilla 2.10 through 2.18, 2.19.1, and 2.19.2 displays a different error message depending on whether a product exists or not, which allows remote attackers to determine hidden products.