Table of Contents
What’s new in Firefox 153?
For Windows users, Firefox 153 offers playback of HDR (High Dynamic Range) videos, although it does require that HDR mode is enabled in the Windows display settings. Laptop screens that only support “HDR video streaming” are not currently supported, nor are smartphone videos in portrait orientation.
With the built-in PDF viewer and editor, you can now merge multiple PDF files by dragging them into the PDF sidebar. You can also insert images as new pages into PDF documents.
If you want to share a link—for example, with your own smartphone—without using a web service (such as Firefox Sync), you can generate a QR code now. Firefox highlights the location-sharing icon in red when a website has access to your location.
fz
The free VPN introduced with Firefox 149 continues to offer a selection of virtual locations, temporarily expanded to 28 countries with unlimited data (until the end of August). The free VPN is currently available to Firefox users in the US, UK, Canada, France, and Germany.
Security updates in Firefox 153
In the Security Advisory 2026-68, Mozilla lists over 63 security vulnerabilities that have been fixed, 60 of which were discovered and reported by external security researchers, including three by OpenAI Codex Security. Mozilla classifies 17 of these vulnerabilities as high risk, and four of them pose a risk of escaping the browser’s sandbox.
A further 35 vulnerabilities are classified as medium risk, with the remainder classified as low risk. The final three entries in the security report summarize an unspecified number of internally discovered vulnerabilities classified as high risk, resulting from programming errors in memory management. The vulnerabilities are grouped according to which apps and app versions are affected.