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.

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.

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.

Bugzilla 2.17.1 through 2.18, 2.19.1, and 2.19.2, when a user is prompted to log in while attempting to view a chart, displays the password in the URL, which may allow local users to gain sensitive information from web logs or browser history.

post_bug.cgi in Bugzilla 2.10 through 2.18, 2.19.1, and 2.19.2 allows remote authenticated users to "enter bugs into products that are closed for bug entry" by modifying the URL to specify the name of the product.

process_bug.cgi in Bugzilla 2.9 through 2.18rc2 and 2.19 from CVS does not check edit permissions on the keywords field, which allows remote authenticated users to modify the keywords in a bug via the keywordaction parameter.