News · written 13 November 2026. A summary for readers, not technical advice — check the sources at the end for the details.

Mozilla released Firefox 160 on 10 November 2026. To see which version you have, open Help → About Firefox.

For everyone

• Picture-in-Picture gets a playback speed setting, from 0.25× to 2×, when the little video window is medium-sized or larger.
• An early Mini Window keeps a tab, or part of a page, in a small window that stays on top. Mozilla calls it an early version and asks for feedback.
• Tired of a site asking again and again to handle email links? A new Never allow button blocks it, and you can undo that in Settings.
• MKV video files with FLAC, MP3 or PCM sound now play.
• Fixes include the first letter you type into the address bar sometimes going missing, and long freezes when signing in to some company intranet sites.

For web developers

• WebTransport: exportKeyingMaterial() now follows the current specification — context is required and there is a new outputLength argument, so code that leaves either out needs updating. The old incomingHighWaterMark and outgoingHighWaterMark options were removed in favour of incomingMaxBufferedDatagrams and outgoingMaxBufferedDatagrams, and the constructor accepts extra headers.
• CSS: the old ::-webkit-input-placeholder now works as another name for ::placeholder.
• The non-standard MozScrolledAreaChanged event is no longer sent to web pages.
• Extensions: runtime.PlatformInfo now reports arm64 instead of aarch64 on ARM64 computers, to match Chrome.

Security

Mozilla's advisory MFSA 2026-125 lists 99 security issues fixed in Firefox 160: 57 High, 24 Moderate and 18 Low. The advisory rates none of them critical. Updating is the fix.

Sources

• Mozilla — Firefox 160.0 release notes (10 November 2026)
• MDN — Firefox 160 release notes for developers
• Mozilla — Security Vulnerabilities fixed in Firefox 160 (MFSA 2026-125)

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