Opera Software patched the newest version of its flagship browser for the first time Wednesday when it released Opera 9.5.1 to fix several flaws.

The update patches bugs in the Windows, Mac OS X and Linux editions, said Opera in notes posted to its Web site.

Among the vulnerabilities addressed in 9.5.1 was one credited to noted researcher Billy Rios that affected only the Windows version of the Norwegian-made browser. "Fixed an issue that could be used to execute arbitrary code, as reported by Billy Rios," said Opera in the 9.5.1 change log. "Details will be disclosed at a later date."

Danish vulnerability tracker Secunia rated the unspecified bug as "highly critical," its second-highest threat ranking.

Other flaws fixed by 9.5.1 included an information disclosure bug that could reveal data stored in memory and another involving digital certificates that were being summarily rejected.

Also included in the update were multiple changes to the user interface, a patch that boosted the browser's stability when accessing Yahoo Mail and a fix for problems related to search engines when upgrading from older Opera editions.

Opera only recently released version 9.5, a major update to the free browser that emphasized security enhancements and bookmark synchronization, among other improvements.

Yesterday's patch update was the first since that launch.