Adobe Systems Tuesday patched its Reader application for the fifth time this year, plugging eight security holes, including one that was reported to the company more than five months ago.

In late May, researchers at Core Security Technologies told Adobe of a critical vulnerability in Adobe Reader and Adobe Acrobat, the free-of-charge and for-a-fee programs, respectively, that handle PDF (Portable Document Format) files. The bug, which could be used by hackers to launch attack code against Windows, Mac or Linux computers, was found in older versions of the software.

Version 8.1.2 of Acrobat and Reader harbor the vulnerability, Core Security said in an advisory issued early Tuesday. Newer versions of the programs, Acrobat 9 and Reader 9, which were released in June, are immune.

Attackers could exploit the buffer overflow vulnerability with specially crafted PDF files, Core Security said.

Reader 8.1.2 was itself prompted by several bugs, some of which were actively exploited in the wild before Adobe could issue the update last February. In June, Adobe released a security update to 8.1.2 to plug yet another hole. That vulnerability had also been exploited by attackers before Adobe reacted.

At the time, a security expert blasted Adobe for what he called an "epidemic" of JavaScript bugs in Reader and Acrobat.

The flaw disclosed Tuesday by Core Security also involved JavaScript. "The vulnerability is caused due to a boundary error when parsing format strings containing a floating point specifier in the 'util.printf()' JavaScript function," said Core Security's advisory.

Core Security uncovered the bug when it dug into an earlier-reported vulnerability in Foxit Reader, a free Reader clone available for Windows and Linux. Although that bug was found to be harmless to Adobe's applications, on further review, Core Security found a second flaw that could, in fact, be used to attack systems.

Core Security reported its findings to Adobe on May 20, but numerous back-and-forths and two patch postponements delayed the coordinated release of security advisories until Tuesday.

Ironically, while Foxit was able to patch against its bug in less than a month, Adobe took more than five times longer to issue fixes for its Acrobat and Reader. Ivan Arce, Core Security's chief technology officer, declined to speculate about why Adobe took so long to patch its programs, other than to point out that Tuesday's update fixed eight flaws altogether.