The Mozilla Foundation has shipped the first patch for its flagship Firefox 1.5 browser to plug a series of security vulnerabilities and memory leaks.

The open-source group has started pushing out Firefox 1.5.0.1 as an automatic update and recommended that all users apply the upgrade to protect against a known denial-of-service bug and several undisclosed security issues.

"We recommend that all users upgrade to this latest version," Mozilla said in a note posted online. In addition to security patches and fixes for memory leak issues, Firefox 1.5.0.1 also promises improved stability and improved support for Mac OS X.

The Foundation did not release details on most of the security flaws being fixed. The published list of patched Firefox vulnerabilities has not been updated to reflect the new browser release.

The exploit was confirmed on Firefox 1.5 on Windows XP SP2 (Service Pack 2) and is caused by an error in the way the open-source browser handles large history information. A successful attacker can fill the browser's "history.dat" file with large history information by tricking a user into visiting a malicious Web site with an overly large title.