Mozilla is working on a new Firefox fix to repair five bugs introduced in last week's security update.
Firefox 126.96.36.199 patched 10 vulnerabilities, including three critical flaws, but also shipped with five regression bugs - problems unintentionally introduced when code was changed to plug other holes.
"Most users won't see any difference or experience any problems," said Mike Beltzner of Mozilla in a posting to the company's development centre blog. "We're working fast to understand and fix these problems, and will shortly be issuing a 188.8.131.52 update to address them."
According to notes from a weekly Mozilla meeting on Firefox, the regression reports began accumulating over the weekend. Firefox 184.108.40.206 was posted for download late on October 17. Three of the five problems were limited to Windows, but two page rendering issues affected all versions of the browser, including those for Mac OS X and Linux.
The Windows-specific bugs included one that disables Firefox extensions after updating. The problem doesn't affect every copy of 220.127.116.11 on Windows - one user said it had hit just one of his four PCs - and can be remedied by deleting a trio of files from the hard drive. Programmers are still working on a fix.
Another under the microscope, however, has no workaround. Firefox 18.104.22.168 crashes on startup on some Windows XP and Vista systems, a listing in Mozilla's bug reporting database said, and although developers quickly came up with a test to reproduce the crash, they seemed unsure whether they were on the right track. "This seems to have been fixed on trunk (regarding the test case) between 2007-08-21 and 2007-08-22," said Martijn Wargers.
"Hmm. I wonder whether we're hitting EM restart weirdness here or something," replied another developer, Boris Zbarsky.
Beltzner said Mozilla hoped to put a new Firefox, version 22.214.171.124, into the pipeline next week.
This isn't the first time that the open-source developer has scrambled to set things right. In March, it released Firefox 126.96.36.199 and 188.8.131.52 to fix several regressions that slipped into the prior versions, which hit the street the month before.