Adobe has confirmed a critical, unpatched vulnerability in its PDF Reader/Acrobat software is being exploited by malicious attackers.

The vulnerability affects Adobe Reader and Acrobat 9.1.3 and earlier versions on Windows, Macintosh and UNIX. Adobe described the in-the wild attacks as limited and targeted, suggesting PDF documents rigged with exploits are being attached to e-mails and sent to business targets.

The exploit only targets Adobe Reader and Acrobat 9.1.3 on Windows.

Adobe’s advisory offers some mitigations:
Adobe Reader and Acrobat 9.1.3 customers with DEP enabled on Windows Vista will be protected from this exploit. Disabling JavaScript also mitigates against this specific exploit, although a variant that does not rely on JavaScript could be possible. In the meantime, Adobe is also in contact with anti-virus and Security vendors regarding the issue and recommends users keep their anti-virus definitions up to date.