Adobe on Tuesday fixed a critical security vulnerability in its Acrobat 9 and Reader 9 applications, which the company said "would cause the application to crash and could potentially allow an attacker to take control of the affected system."

The bug was first reported in late February, and affects Adobe Reader 7 and 8, and Acrobat 7 and 8, as well. Adobe plans to make updates available for those earlier software versions by 18 March.

In addition to the security hole, the updates also address issues with 3-D, forms, hosted services, portfolios, and document security and digital signatures.

Some of the changes include the enabling of full-screen mode for portfolios when a PDF is displayed in the portfolio preview window, Keychain support for interfacing with smartcards and USB tokens, and support for a new USPS barcode that came into effect in January 2009.

The updates are available from Adobe's web site .