Firefox 153 landed this week with one of Mozilla’s larger feature updates in recent memory, pairing a security refresh covering 63 vulnerabilities with new capabilities that address long-standing user requests.
The headline addition is HDR video playback on Windows. Users with HDR-enabled displays and the feature activated in Windows display settings can now view high-dynamic-range content directly in the browser. Mozilla notes that laptop screens limited to HDR video streaming mode and smartphone-shot portrait videos are not supported.
A new QR code generator lets users share links without routing data through third-party services or Firefox Sync, a privacy-forward approach that generates codes entirely on-device. The PDF viewer also received an upgrade: users can now merge PDF files by dragging them into the sidebar and insert images as new pages.
On the security front, the browser ships with 63 vulnerability fixes, 17 of which are classified as high-risk. Four of those high-risk flaws are capable of escaping the browser’s sandbox protection, making them particularly dangerous. Mozilla credited external researchers for reporting 60 of the 63 bugs, including three discovered by OpenAI Codex Security.
The update also introduces a visual cue for location sharing: the location indicator in the address bar now turns red when a website has access to the user’s geographical position.
Some users have reported crashes after updating, with internal files failing to load during the update process. Mozilla recommends downloading a fresh installer and reinstalling over the corrupted installation, noting that bookmarks and passwords are stored separately and will not be lost.
The Extended Support Release channels also received updates. Firefox ESR 140.13.0 addresses at least 32 vulnerabilities, while ESR 115.38.0, still maintained for Windows 7, 8.1, and older macOS versions, covers at least 14 flaws including 2 critical ones. ESR 140 will be superseded by ESR 153 in October 2026, while ESR 115 is slated for security updates through March 2027.
Sources: PCWorld (Jul 29, 2026); Mozilla Security Advisories