The most serious flaw could allow a malicious attacker to take complete control of a system, Opera said in an advisory.
A second flaw, rated "highly severe," could allow error messages to leak onto unrelated sites
Scripting error messages are normally available only to the page that caused the error. In some cases, the error messages could be passed to other sites as the contents of unrelated variables, and may contain sensitive information. If those sites write the content into the page markup, this could allow cross-site scripting, using code provided by the attacking site. This issue only affects installations that have enabled stacktraces for exceptions, these are disabled by default.
Opera also patched a third "moderately severe" flaw but details on this issue were not released.
Opera users should immediately upgrade to version 10.10 which includes the patches for these issues.