This guide provides the official download information, installation steps, and critical security context for using this "end-of-the-road" browser.
https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/win32/
Mozilla has removed direct "easy" download buttons for this version, but the installer is still hosted on their official FTP servers. Always use official sources to avoid malware often bundled in third-party "legacy" software sites.
To run Firefox 52.9.0 ESR, your system must meet these minimum requirements: Cannot install 52.9.0esr on XP SP3 | Firefox Support Forum
Even if your computer has a 64-bit CPU, you must download the 32-bit (win32) version. The 64-bit builds of Firefox 52 require Windows 7 or higher. System Requirements for Windows XP
Navigate to your preferred language folder (e.g., /en-US/ ) and download the .exe file.
Firefox 52.9.0 ESR for Windows XP: The Ultimate Guide For users still running Windows XP, finding a functional web browser is a significant challenge. (Extended Support Release) is widely recognized as the final official version of Firefox to support Windows XP and Windows Vista.
Firefox v52.9.0esr on Archive.org .