Note #Mullvad #Browser 13.5.4 and 13.5.5 were skipped because they were Tor Browser only numbered releases.
All Platforms

Updated #Firefox to 115.16.0esr
Updated #NoScript to 11.4.40
Bug 356: Rebase Mullvad Browser Release onto Firefox 115.16.0esr [#mullvad-browser]
Bug 42832: Download spam prevention should not affect browser extensions [tor-browser]
Bug 43173: Backport security fixes from Firefox 131 [tor-browser]

Linux

Bug 334: When set as default browser on Linux in standard mode, links don't open correctly [mullvad-browser]

https://github.com/mullvad/mullvad-browser/releases/tag/13.5.6