Security watchers are warning of a critical flaw affecting older versions of Adobe Reader.

Hackers might be able to exploit the bug using specially crafted pdf files with JavaScript content, Core Security warns. Ivan Arce, CTO at Core Security, said the security bug was discovered while investigating a previously disclosed problem in Foxit, an alternative pdf viewer package.

Successful exploitation against the Adobe Reader flaw would involve tricking users into opening a laced pdf file. The flaw only affects users of Adobe Reader 8, which was replaced by Adobe Reader 9 in June 2008. Nonetheless Core argues that many users are still running older versions of the software and are therefore at risk of attack.

Adobe has issued a security patch to fix the flaw, which affects versions 8.1.2 and below of Adobe Reader. If applying the update isn't immediately possible then disabling Javascript functionality should suffice as a workaround. ®

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