US-CERT, the U.S Department of Homeland Security's cybersecurity arm, on Wednesday issued two warnings.

The first notice concerns the public availability of exploit code for RealPlayer 11 build 6.0.14.748. US-CERT said it will provide additional information when available.

The second notice concerns a vulnerability in Flash (.swf) files that may allow a remote, unauthenticated attacker to execute a cross-site scripting (XSS) attack on vulnerable systems. The vulnerability has to do with the way that input is validated when passed to an embedded ActionScript and JavaScript in the Flash file.

Flash authoring tools, said US-CERT, may generate Flash files that are vulnerable.

Rich Cannings, a senior information security engineer at Google, has detailed the risks in a Google Docs file. "Simple Google hacking queries reveal that hundreds of thousands of SWFs are vulnerable on the Internet, and a considerable percentage of major Internet sites are affected," he said. "We are only reporting XSS vulnerabilities that have been fixed by the vendors."

Cannings notes that applications that automatically generate .swf files like Adobe Dreamweaver, Adobe Acrobat Connect, InfoSoft FusionCharts, and Techsmith Camtasia were vulnerable but have been fixed. He says other products remain vulnerable and that he will publish details once patches were available.

Cannings calls for Web site owners to serve automatically generated .swf files from numbered IP addresses or other "safe" domains that do not utilize cookies with sensitive information and cannot be used for phishing. He recommends that Flash developers test their SWF content with Stafano Di Paola's SWFIntruder. "If you don't, others will," he says.