According The Official Microsoft Blog, a patch for the recently discovered security vulnerability in Internet Explorer, versions 6 through 11, went live at 10 a.m. PDT yesterday, 1 May 2014. Adrienne Hall, General Manager, Trustworthy Computing, Microsoft, also writes:
Even though Windows XP is no longer supported by Microsoft and is past the time we normally provide security updates, we’ve decided to provide an update for all versions of Windows XP (including embedded), today. We made this exception based on the proximity to the end of support for Windows XP.
She does, however, go on to advise all users of XP to upgrade as soon as possible.