Mozilla Foundation strongly advises against using Firefox 52.9.0 ESR on any device connected to the internet. Since June 2018, several high-profile security vulnerabilities have been discovered in the browser engine (CVE-2019-11707, CVE-2020-15664, etc.) that will never be patched for this version.
Using this browser on a banking site, email provider, or social media puts you at immediate risk of:
Only use this version for offline, legacy, or isolated system purposes.
Mozilla no longer hosts old ESR versions on its main site. However, the official archive is available here: firefox version 52.9. 0 esr download
From there, navigate to:
Let’s be realistic. In 2025, using Firefox 52.9.0 ESR as your daily driver on the open internet is not recommended. Here is what will break:
Download the .exe (Windows), .dmg (macOS), or .tar.bz2 (Linux) file. Only use this version for offline, legacy, or
Direct download example (Windows 32-bit, English):
https://archive.mozilla.org/pub/firefox/releases/52.9.0esr/win32/en-US/Firefox%20Setup%2052.9.0esr.exe
(Always verify the SHA-256 hash if you are paranoid. Mozilla provides checksums alongside the files.)
Do not use Firefox 52.9.0 ESR as your daily browser or for any internet banking, email, social media, or general browsing. From there, navigate to: Let’s be realistic
Malicious extensions – Legacy addons are not vetted via Mozilla’s modern review process.
Recommendation: Use this browser only in a fully isolated VM, air-gapped machine, or for very specific internal LAN tasks with no internet access.
