Malware writers have created a new worm that installs a new browser, plays screeching music and dumps a graphic on the victim's desktop.

Security researchers have identified an "insidious" threat affecting Yahoo Messenger.

If you're one of the tens of millions of Yahoo users asked to upgrade your instant-messaging software this week, be on your toes: The update can open the door to unwanted PC houseguests--and setting changes--by default.

A new worm and a phishing scam are targeting members of the America Online and Yahoo instant messaging networks, security companies warned Tuesday in the US.

Hackers are exploiting interest in the new Star Wars film to harvest Yahoo! login credentials. The attack is initiated when a user clicks on a malicious link (yahoopremium.bravehost.com/STAR_GAMES) sent to them from a user on their buddy list.

Security researchers have discovered a denial of service vulnerability involving Yahoo!'s popular instant messaging client. Hackers can potentially disconnect users from chat sessions by sending malformed packets to Yahoo! Messenger servers.

Yahoo's free instant-messaging service is being targeted by phishers attempting to steal usernames, passwords and other personal information.

Yahoo Messenger users are vulnerable to two security holes, the more serious of which could lead to the execution of malicious code on a user's system, Yahoo has warned.An update available from Yahoo's site fixes the flaws, which affect versions of Messenger up to 6.0.0.1750, and would be found in any version downloaded before 15 February.

Yahoo Inc. has released a new version of its instant messaging application to fix a pair of security vulnerabilities that could put users at risk of code execution attacks.

The company has issued a fix for a PNG flaw that could put Yahoo Messenger users at risk of buffer overflow attacks.

Yahoo! posted to its Instant Messenger site last week a patch plugging a hole in Yahoo IM's use of portable network graphics (PNG) that could make a computer system vulnerable to crashes and attacks while a user surfs the Web.

Yahoo has posted a security patch for a flaw in its instant-messaging software that could make a computer system vulnerable to crashes and attacks while a user surfs the Web.

Yahoo's instant messenger will no longer allow communications from people using third-party services such as Trillian.Yahoo on Wednesday began blocking Cerulean Studios' Trillian software from communicating with its instant-messaging service,in its latest step to fence its popular client from third-party integrators.

Yahoo has fixed a bug in its instant messenger application after it was found to be vulnerable to buffer-overflow errors when receiving files, potentially leaving PCs open to attack

The hole could have allowed an attacker to launch a computer worm or run malicious code on a victim's computer when an e-mail containing the code was opened, according to Finjan Software of San Jose, California, which discovered the problem.