Firefox 91.0.1 fixes stability and security issues

Mozilla will release Firefox 91.0.1 and Firefox 91.0.1 ESR later today. The two new versions of the organization's Firefox web browser fix security and stability issues of previous versions of the browser.

Mozilla released Firefox 91, a new major version of the browser and new Extended Support Release base, last week. The new version of Firefox added a HTTPS-First policy for the browser's private browsing mode, re-added the Simplified Printing option and fixed security issues among other things.

Firefox 91 is also the first version that removed options to disable the browser's new Proton interface using advanced preferences.

Firefox 91.0.1 will become available later today. It is already available on Mozilla's distribution server, but it is not recommended to install this version as there is no guarantee that it is indeed the final version.

Most Firefox installations will be updated automatically via the browser's built-in updating system. Downloads will also become available later today on the official Mozilla website.

You can display the current version and run a manual check for updates by going to Menu > Help > About Firefox.

Mozilla highlights four changes in Firefox 91.0.1, but not all information is available at this point. Firefox 91.0.1 comes with "various stability fixes" and a security fix. The security information is not yet available; it will be published after Firefox 91.0.1 has been released officially. Additional information about the stability fixes is not available either.

The two remaining issues are described in detail:

• An issue caused buttons on the browser's tab bar to be resized when "certain websites" were loaded.
• An issue caused tabs from private browsing windows to be visible in non-private windows when viewing "switch-to-tab results in the address bar panel".

Both of these bugs have been fixed and should not be experienced anymore by Firefox users once the browser has been updated to the new version.

Closing Words

The official release notes do not reveal the severity of the security issue. You may want to pay attention to the Mozilla Foundation Security Advisories website, as information will be listed on that page later today.

Firefox 91.0.1 fixes stability and security issues

Frontpaged: Mozilla Forefox Browser 91.0.1