Synergy Dragon Alpha

v0.5.0 (September 29, 2026)

Security

• CVE-2026-63409: A malicious server could make a client read outside its memory by sending an options message with an odd-length list.
• CVE-2026-65832: A malicious server could make a client read outside its modifier table by sending a modifier mapping that pointed past its end.
• CVE-2026-65976: A connected computer could make another use ever more memory by sending clipboard data beyond the declared and configured size limits.
• GHSA-vxgx-6p4m-fv83: A malicious server could stop a client by sending a single-byte keyboard layout message.

Features

• Copy and paste now shares up to 128 MB by default, with a new size limit setting that replaces the old one.
• The status bar shows each clipboard on its way between computers, confirms when it lands, and says when one was cut off or was over the size limit.

Enhancements

• Images are now sent in the format they were copied in, instead of as uncompressed bitmaps, so more apps can paste them and large screenshots and photos fit well within the limit.
• Animated GIFs, SVG images, RTF rich text, WebP and TIFF images are now shared as they are, instead of being converted or left out.
• Large clipboards no longer hold up the mouse: a clipboard is now sent in small pieces behind your keyboard and mouse input, once the mouse comes to rest on the other computer.
• A computer now says its name is taken when the primary turns it away because another computer with the same name is connected, instead of reading Not sharing.
• On a Mac, the password prompt that installs the background service is titled Synergy Dragon Alpha, and the window behind it says what the password is for and waits for as long as you need.

Bug fixes

Windows

• Stopped a large copy freezing the keyboard and mouse until the copying app had finished preparing its data.
• Stopped a Windows client disconnecting partway through a large clipboard sent over TLS.
• Corrected clipboard detection on a Windows client so every copy is shared, not only the first one after it receives a clipboard.
• Restored sharing of images that apps copy only as PNG, JPEG or other image files.
• Restored pasting an image on a Windows client when it was copied on a macOS server.
• Stopped encrypted connections holding a processor core at full use after a large clipboard transfer.
• Stopped a modifier key held while crossing from a client back to a Windows server staying pressed on the client after it is released.
• Restored Shift+Space and Ctrl+Space reaching a macOS client when the Korean input method is active on the Windows server.
• Stopped a crash converting some clipboard images on a screen switch.
• Stopped a one-byte buffer overwrite and an out-of-range read when looking up a loaded module.

macOS

• Stopped sharing never starting on a Mac where macOS refuses to run the app's background helper, which the app now starts itself.
• Corrected opening the app after quitting it from the tray, which used to fail with a dialog whose only choice was Quit.
• Corrected installing the app again so it repairs a broken install: the app now runs the version you just installed instead of the copy it already had.
• Corrected the disk image so it shows where to drag the app, and the app icon can be picked up anywhere inside its circle rather than only by its edge.
• Restored sharing of images copied on a Mac, and images sent to a Mac are now written as PNG, JPEG and TIFF so Mac apps can paste them.
• Stopped text shared to a Mac getting old-style carriage-return line breaks.
• Stopped a copy made just before moving off a Mac being missed.
• Stopped copying a list of files or links on a Mac hanging the clipboard read.
• Restored clicks bringing a background application to the foreground on macOS 27, and dragging windows by their title bar.
• Corrected Right Option, Right Command, Right Control and Right Shift so they arrive on a macOS client as right-hand keys rather than left-hand ones.
• Corrected punctuation typed on a macOS server with a Chinese or Japanese input method active, so it arrives on other computers as ASCII punctuation rather than the input method's.
• Corrected a cause of wrong symbols on a Japanese keyboard layout with a Windows server and a macOS client, including after a reconnect.
• Stopped mouse movement reaching the application under the server's cursor while the cursor is on a client.
• Stopped a multi-display macOS server switching back to itself within a second or two of the cursor crossing to a client.
• Stopped shake to locate enlarging the server's cursor while the mouse is being used on a client.
• Stopped memory growing for the life of the process during long sessions.
• Stopped an event tap registration leaking each time a client connects and disconnects.
• Stopped a crash at startup or on a keyboard layout switch when an input source reports no languages.

Linux and Wayland

• Restored image copy and paste on X11 with apps that use PNG or JPEG.
• Stopped the cursor snapping to the left edge of the client and getting stuck when a Wayland server is placed to the right of it.
• Restored the cursor leaving a multi-monitor Wayland server, which now keeps only the outer edge of the combined monitors.
• Corrected where the cursor returns on a multi-monitor Wayland server, so it comes back at the matching position rather than shifted or on another monitor.
• Stopped the cursor jumping to the center of the screen when the compositor recreates its input devices, for example when the brightness or volume popup opens.
• Stopped a drag on a Wayland server switching screens part way through.
• Stopped a Wayland client holding on to its input grab when idle, so its display can sleep or lock.
• Stopped the numpad needing NumLock turned back on after each switch to a client from a Wayland server.
• Corrected scrolling on a Wayland client, so steps smaller than one wheel click add up to whole clicks instead of being dropped.
• Stopped a modifier being left stuck when an X11 client applies a refreshed keyboard map, by releasing keys held from the server first.
• Stopped a deadlock in the X11 clipboard.
• Stopped a "pure virtual method called" abort when a Wayland server fails to start, for example when the port is already in use.
• Stopped a small memory leak each time the compositor closed and reopened the input session.
• Stopped a client crashing when the server's hostname does not resolve; it now retries.

All computers

• Corrected monitors in the layout so they sit where the desktop places them, with no gaps between them, and carry the desktop's own numbers. On a computer with a scaled monitor, the cursor now crosses the desktop's real width too.
• Stopped a copy of the core left behind by an earlier run holding on to a computer's name, which left it reading Not sharing while the keyboard and mouse still crossed to it.
• Stopped a client dropping a healthy connection while receiving a large clipboard.
• Stopped a client disconnecting when the server sends a clipboard larger than the client's own limit, so transfers up to the server's limit go through.
• Stopped every copy on a Mac or Windows computer being sent twice.
• Restored timing below a second, so settings such as the switch delay take effect as set.
• Corrected scrolling from mice that report steps smaller than one wheel click, which now add up to whole clicks on the server instead of being dropped.
• Stopped possible crashes when a client disconnects, or the server stops, during a clipboard transfer or a screen switch, and when a client is disconnected over a malformed message.
• Corrected clipboard handling so a truncated clipboard header is rejected before it is read.
• Stopped the cursor jumping to the top-left corner on return to a client in relative mouse mode.
• Restored a client working with a server on an older protocol version, by negotiating down to it.