Mozilla deploys Firefox safety net for corporate mindreaders
Security fixes applied to as-yet-undisclosed older builds
Mozilla has pledged to update old versions of Firefox with security fixes, granting enterprises extra time to test and deploy major upgrades of the browser safe in the knowledge that vulnerabilities in existing installations will be patched.
It's not clear which builds will fall onto Mozilla's safety net, however, so IT departments are more or less left to bet on running the right versions on their corporate machines.
Announced on Tuesday, the Firefox Extended Support Release (ESR) will maintain builds of desktop Firefox for a period of 54 weeks, covering nine full releases of Mozilla's browser, the non-profit said.
Each ESR will be updated with point releases that will be limited to what Mozilla called "high-risk/impact security vulnerabilities" - those risks considered "critical" and "high". Functional enhancements and stability fixes in new point releases won't be back ported.
Once the 54 weeks is up, that's it according to Mozilla:
When an ESR reaches end-of-life, no further point releases or chemspill updates will be offered for that ESR, and an update to the latest supported version of the ESR (or Desktop Firefox, if the ESR for that platform is discontinued) will be offered to users of the end-of-lifed version.
The versions of Firefox that will qualify as ESRs is left to Mozilla's discretion. Based on the original ESR proposal, outlined by Mozilla vice-president of products Jay Sullivan here , it will be the non-profit that anoints the versions of Firefox that receives extended coverage. Sullivan's blog talks of an ESR period of 42 weeks but that has been pushed out 54 weeks under the finished plan.
Based on a handy chart, here  and some accompanying text from Mozilla it does seem that ESRs will not accompany each version of Firefox. This means you will have to pre-empt Mozilla in picking the versions of Firefox considered important enough to qualify for ESR support.
Nobody from Mozilla was available to clarify this aspect of the ESR at the time of publication. ESRs will start with Firefox 10, currently in beta.
The ESR programme was introduced by Mozilla's Enterprise Working Group after the rapid release cycles seen in 2011 were criticised for not giving enterprises enough time to test new versions of Firefox with their apps, extensions and plug-ins.
At one point last year, one of Mozilla's top figures Asa Dotzler dismissed the importance of corporate users in response to disapproval from an adopter who'd spent months readying 500,000 corporate users for Firefox 4 when Mozilla released Firefox 5.
Mozilla chief executive Gary Kovacs subsequently tweeted  that enterprise customers are important to Mozilla and Firefox. "Enterprises are built of people, and Mozilla is fundamentally about people. We support Firefox users wherever they are," he said. ®