You can get the latest copy of the program from the Wireshark website at https://www.wireshark.org/download.html. The download page should automatically highlight the appropriate download for your platform and direct you to the nearest mirror. Official Windows and macOS installers are signed by the Wireshark Foundation. macOS installers are also notarized.
A new Wireshark version typically becomes available every six weeks.
If you want to be notified about new Wireshark releases you should subscribe to the wireshark-announce mailing list. You will find more details in Section 1.6.5, “Mailing Lists”.
Each release includes a list of file hashes which are sent to the wireshark-announce mailing list and placed in a file named SIGNATURES-x.y.z.txt. Announcement messages are archived at https://www.wireshark.org/lists/wireshark-announce/ and SIGNATURES files can be found at https://www.wireshark.org/download/src/all-versions/. Both are GPG-signed and include verification instructions for Windows, Linux, and macOS. As noted above, you can also verify downloads on Windows and macOS using the code signature validation features on those systems.