Firefox 3.5.12 fixes the following issues found in previous versions of Firefox 3.5:

• Fixed several security issues.
• Fixed several stability issues.

Please see the complete list of changes in this version. You may also be interested in the Firefox 3.5.11 release notes for a list of changes in the previous version.

Firefox 3.6.9 fixes the following issues found in previous versions of Firefox 3.6:

• Introduced support for the X-FRAME-OPTIONS HTTP response header. Site owners can use this to mitigate clickjacking attacks by ensuring that their content is not embedded into other sites.
• Fixed several security issues.
• Fixed several stability issues.

Please see the complete list of changes in this version. You may also be interested in the Firefox 3.6.8 release notes for a list of changes in the previous version.