WordPress Release: 3.9.18

TL;DR

WordPress 3.9.18 is a maintenance release that fixes a critical bug affecting audio and video functionality while also improving the build and testing infrastructure. The update addresses an issue where sanitizing ID3 tag data was corrupting blob data, which could break media playback. Additionally, several improvements to the Travis CI testing environment were implemented to enhance performance and efficiency of the testing process.

Highlight of the Release

• Fixed critical bug affecting audio and video functionality when handling ID3 tag data
• Improved build and testing infrastructure for better development workflow
• Optimized Travis CI test matrix to speed up build processes

Migration Guide

No migration steps are required for this update. This is a maintenance release that can be applied through the standard WordPress update process without any special considerations.

Upgrade Recommendations

This update is highly recommended for all WordPress 3.9.x users, especially those who use audio and video content on their sites. The fix for ID3 data sanitization resolves a critical issue that could prevent media files from functioning correctly.

To update:

1. Back up your website before updating
2. Update through the WordPress dashboard or download the update from wordpress.org
3. No additional steps are required after updating

Bug Fixes

Fixed Audio/Video Functions When Sanitizing ID3 Data

This release fixes a critical bug where running wp_kses_post_deep() on ID3 tag data was corrupting blob data, which caused audio and video functionality to break. The issue occurred when WordPress attempted to sanitize ID3 metadata from media files, resulting in corrupted data that prevented proper playback and display of media files.

References: #40075, #40085

New Features

No new features were added in this maintenance release. WordPress 3.9.18 focuses on bug fixes and performance improvements to the build and testing infrastructure.

Security Updates

No specific security fixes were included in this release. However, keeping WordPress updated to the latest version is always recommended as a security best practice.

Performance Improvements

Build and Test Infrastructure Improvements

Several performance enhancements were made to the build and testing infrastructure:

• Disabled Xdebug when testing on Travis CI to increase performance (see #39978)
• Optimized the test matrix on Travis by removing PHP 5.3 and 5.4 jobs to speed up the 3.9 branch build (see #40407)
• Reversed the order in which Travis jobs run on the 3.9 branch for better efficiency (see #39705)
• Added logic to skip time-sensitive tests (copyright year and PHP/MySQL version requirements) when tests are run on branches on Travis (fixes #39486)

Impact Summary

WordPress 3.9.18 addresses a significant bug that affected audio and video functionality when handling ID3 tag data. This issue could cause media files to fail to play or display correctly on WordPress sites. The fix ensures that ID3 metadata is properly handled without corrupting the underlying blob data.

Additionally, the release includes several improvements to the build and testing infrastructure, which benefit developers working with the WordPress codebase. These changes optimize the testing process on Travis CI by disabling Xdebug, trimming the test matrix, and improving the efficiency of test runs.

While this is primarily a maintenance release with no new features, the bug fix for media functionality is important for sites that utilize audio and video content. Site administrators and content creators will benefit from the restored reliability of media playback and display.