Yahoo Inc. has issued a security update to its popular instant messaging service to fix broader vulnerabilities in an advanced graphics format.
Late on Tuesday, Yahoo posted a security update for its Windows version of Yahoo Messenger to fix a series of vulnerabilities in the PNG (portable network graphics) library, or libpng. The library provides a set of graphics routines for PNG files; PNG is an alternative graphics format to GIF.
The PNG library holes, as previously reported, could allow an attacker to crash programs or execute attack code. A range of software makers have already released patches to fix the issue. Among them, Apple Computer Inc. updated Mac OS X, and the Mozilla Foundation released new versions of its open-source browsers.
Yahoo released the fix for users of Yahoo Messenger 6.0 for Windows because it uses the open-source PNG format in limited areas of its IM client to display images, said Yahoo spokeswoman Terrell Karlsten.
"Beginning today, we are notifying users who are currently running Windows versions 6.0 to install the security update," she said in a statement Friday. "Upon logging into Yahoo Messenger, users will be prompted with a message window that invites them to update their service."
According to a security note on the Yahoo Messenger Web site, there have been no known exploits of the vulnerabilities. Users also can download the latest version of Yahoo Messenger for Windows to fix the issue.
Yahoo learned of the PNG library vulnerabilities from a U.S. Computer Emergency Readiness Team security bulletin issued last week.
Earlier this week, America Online Inc. released a beta version of AOL Instant Messenger 5.9 that included a fix for a separate security vulnerability that could open AIM users to a attack through AIMs "Away" feature for automatically sending presence notifications.