Security experts have urged users to be cautious following the discovery of a new zero-day attack on Adobe's Reader and Acrobat platforms.
Adobe said that its Product Security Incident Response Team (PSIRT) is investigating an attack which uses modified PDF files to exploit the vulnerability.
"Adobe is aware of a report of a vulnerability in Adobe Reader and Acrobat XI (11.0.1) and earlier versions being exploited in the wild," the PSIRT said.
"We are currently investigating this report and assessing the risk to our customers."
Word of the attacks comes just hours after Adobe posted a security update to address flaws in its Flash and Shockwave platforms. The company gave no word on when a possible Reader update would be released.
Adobe's Reader and Acrobat platforms have historically been favourite targets for malware writers. The PDF file attacks are second only to Java exploits as the most commonly-targeted platforms in the wild.
Ross Barrett, senior manager of engineering for security firm Rapid7, noted that the casual way in which many users handle documents makes PDF attacks particularly dangerous.
"On any given day I would view a PDF attachment that I am not explicitly expecting with a high degree of suspicion, and this is just confirmation of those concerns," Barrett explained.
"The major risk will be via compromised 'safe' websites which are serving the malware unbeknownst to their legitimate operators."