- Fix some issues with older browsers in the administration area.
- Fix an issue where a theme may not preview correctly, or its screenshot may not be displayed.
- Improve plugin compatibility with the visual editor.
- Address pagination problems with some category permalink structures.
- Avoid errors with both oEmbed providers and trackbacks.
- Prevent improperly sized header images from being uploaded.
Version 3.4.2 also fixes a few security issues and contains some security hardening. The vulnerabilities included potential privilege escalation and a bug that affects multisite installs with untrusted users. These issues were discovered and fixed by the WordPress security team.