Microsoft is making an about face and issuing a security fix for an Internet Explorer problem facing Window XP as well as all other Microsoft operating systems.
The fix is being issued today for all versions of Internet Explorer from 6 through 1 ahead of next week's Patch Tuesday for May, indicating Microsoft thinks it represents a significant threat.
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This includes Windows XP, which fell out of support April 8 and therefore shouldn't receive a patch.
"I think this underscores the importance of this patch, and the priority with which it should be deployed," says Trey Ford, the Global Security Strategist for Rapid7. "Corporate and private users should prioritize downloading (testing, where required by change controls) and deploying this patch."
A Microsoft blog announcing the fix Microsoft doesn't say why it's had a change of heart:
"At approximately 10 am PDT, Microsoft will release a security update to address an issue affecting Internet Explorer," says Dustin Childs, who is the group manager for Response Communications in Microsoft's Trustworthy Computing group. "Microsoft has also made the decision to issue the security update to Windows XP customers."
He quotes Adrienne Hall, general manager of Trustworthy Computing as saying, "The security of our products is something we take incredibly seriously. When we saw the first reports about this vulnerability we decided to fix it, fix it fast, and fix it for all our customers."
Childs notes that Microsoft's official position is not to support Windows XP and to encourage customers still using it to upgrade to Windows 7 or 8.1.
Most customers with automatic updates enabled need to take no action to receive the Internet Explorer fix.
As a rule, Microsoft issues patches once a month on Patch Tuesday, reserving out-of-band patches for vulnerabilities deemed severe or for which there are active exploits in the wild, which is the case here.
"Out of band updates are a big deal," says Ford. "To interrupt a scheduled development cycle for an emergency patch, or out of band' release is a noteworthy event where a vendor is placing the public good ahead of their development and delivery lifecycle."
Tim Greene covers Microsoft and unified communications for Network World and writes the Mostly Microsoft blog. Reach him at tgreene@nww.com and follow him on Twitter @Tim_Greene.
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