Ivan Ivan has discovered a weakness in Yahoo! Messenger, which potentially can be exploited by malicious people to cause a DoS (Denial of Service).

The weakness is caused due to an error within the handling of certain messages. This can be exploited to crash another user's Yahoo! Messenger client via a specially crafted message that contains a non-ascii character.

For example:
s:[space]msg[alt+0160]:---------------------------------------------iframe onload=$InlineAction()>:)

Successful exploitation requires that the user has not configured the application to ignore malicious users that are not on his Messenger list.

The weakness has been confirmed in version 7.5.0.814. Other versions may also be affected.

Solution
Configure Yahoo! Messenger to ignore users that are not in the Messenger list.

Provided and/or discovered by
Ivan Ivan

Changelog
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