Fixed security flaws in upgrade and Whisper downloads (failed HTTPS was retried over HTTP, certificate errors could be ignored, and a downloaded file could be used without a trusted digest).
Fixed Mask: Draw (Glaxnimate) filter, Operation > Subtract for 8-bit processing mode (broke in version 25.12).
Fixed using Size, Position & Rotate with Mask: Apply filters (broke in version 25.12).
Improved audio quality by removing a conversion to 16-bit integer and keeping the pipeline in 32-bit float.
Fixed LV2 external audio plugins not loading on Windows (unless LV2_PATH environment var set explicitly).
Fixed VA-API HEVC hardware encoder on Linux.
Fixed Show in Folder not working with non-ASCII characters on Linux.
Fixed Import Subtitles from File not working on Windows.
Fixed Subtitles view shows incorrect duration (broke in version 26.8).
Fixed moving Timeline clip next to another with snap while zoomed out may insert 1 blank frame.
Fixed copy and pasting a Timeline transition corrupt audio in the pasted transition.
Fixed window title bar missing on Linux with Settings > Display Method > Vulkan.
Fixed marker unexpectedly deleted when moving a clip to the left with Ripple Markers on.
Fixed keyframes on Timeline > Split after a transition.
Fixed Export job may report failure even though file was completed successfully.
Fixed some buffer overflow security issues in PGM/wipe reading in MLT and Set Equirectangular in Shotcut.
Fixed projects deleted from disk still appear in Projects.
Fixed Ctrl+Up and Ctrl+Down cannot change current track when Timeline loses focus.
Fixed Player > External Monitor > DeckLink (and related such as UltraStudio) HDMI/SDI may deadlock.
Fixed MLT XML nested clip's length (duration) not updated, now updates when selected but needs manual trim to increase clip.
Fixed redundant context menu on text edit controls in filters on Windows (broke in v26.8).
Fixed open project on a mounted CIFS/SMB share on Linux kernel 7.1 and above.
Fixed possible crash when trying to add subtitle item in the last half second of the timeline.
Hardened MP4 parsing in Set Equirectangular in Properties and export job context menu.
Changed Settings > Leave Safe Mode to an always-present Allow External Plugins checkbox that defaults to off. This helps prevent the problem that some VST2 plugins on Windows and macOS are causing startup and shutdown (including export) problems.
Detect a stuck application startup to automatically disable external plugins.
Added Automatic Audio Ducking for audio to timeline track Properties.
Changed Adjust Clip Gain for timeline clips to require Ctrl+Alt (option+command on macOS) to drag. This makes it safe from inadvertent changes while selecting and dragging clips. So, now that setting defaults on again. Also, a tooltip was added to the clip's audio line.
Added volume control and audio level meter/indicator to Timeline track headers. This effectively makes the track header column a mixing console without needing to clutter the UI with a new panel. The gain filter this adds to the track is keyframable.
Added Timeline > Generate > Adjustment Clip. This is a dummy video clip that contributes no video. Instead, its filters apply to the composite of all video tracks below it.
Added application.triggerAction(name), multitrack.clipStart(), and timeline.split() functions for scripts.
Added a context menu with Copy to Missing Files dialog and View > Resources.
Improved the performance of the Timeline: moving clips to another track, zooming, undo for many operations (except for ripple move/trim).
Improved the appearance of the user interface to be more modern with rounded corners in many places.
New logo
Upgraded FFmpeg to version 9.0

Full Changelog: https://github.com/mltframework/shotcut/compare/v26.8.1...v26.9.27