Mozilla has decided to issue at least one more security update for that edition, which shipped in January 2010. The update, to be pegged 3.6.19, will be released alongside Firefox 6 when the latter ships on Aug. 16.

The company has not disclosed other parts of its plan to declare Firefox 3.6 at "end of life," or EOL. Although Mozilla held a meeting Tuesday in its Mountain View, Calif. office to discuss Firefox 3.6's retirement, unlike its usual practice the company did not publish notes from that meeting.

The demise of Firefox 3.6 from support would put users who have stuck with the older version in a bind.

IBM, for example, selected Firefox 3.6 last summer as its default browser for employees.

John Walicki, the manager of workplace and mobility in the office of IBM's CIO, has complained about the retirement of Firefox 4, saying that it would force him to make a tough decision.