Nokia confirmed Thursday its widely used Series 40 operating system has security vulnerabilities that could allow stealth installation and activation of applications.

But the company is evasive on whether it paid ¬20,000 (US$29,500) to researcher Adam Gowdiak of Security Explorations, who wanted payment for the six-month effort spent finding the flaws.

Gowdiak would not disclose if he was paid, but said that only reputable, vetted companies that pay would get the full research, which amounted to 180 pages and 14,000 lines of proof-of-concept code.

Nokia has a complete copy of Gowdiak's research, said Mark Durrant of Nokia's corporate communications.

The mobile giant's position could rekindle the debate among security professionals on whether voluntary research should be rewarded by vendors whose products are affected.

Vendors typically steer clear of paying researchers for vulnerability information and alternatively encourage what they term is "responsible disclosure," or a discrete notification before vulnerability information is made public. Vendors also don't want to be at the mercy of vulnerability hunters, who could threaten to turn information on a flaw over to hackers.

"It would be very easy for there to be an idea that you can hold companies to ransom," Durrant said. "The reality is he [Gowdiak] has done a significant amount of research, and clearly it's understandable he wants to find a way to monetize that."

Gowdiak, a researcher in Poland, said earlier this month he had found problems with Java 2 Micro Edition, (J2ME) an application framework for mobile devices, as well as the Series 40 OS. Nokia claims Series 40 is the mostly widely used mobile device platform.

Gowdiak has done research on the Java Virtual Machine and wrote on his Web site that he worked at one time for its developer, Sun Microsystems.

While details on the vulnerabilities are limited, Gowdiak has said an attack could be mounted by sending maliciously crafted messages to a particular phone number.

Nokia said some of its Series 40 products are vulnerable to an attack that could result in the secret installation of applications. The company said it has also found earlier versions of J2ME could allow privilege escalation or access to phone functions that should be restricted.

"Our testing has been concentrating on products that might have both of the claims present," according to a Nokia statement.

Nokia said it isn't aware of attacks against Series 40 devices, and the problems do not represent a "significant risk." Durrant said that conclusion is based on the fact the vulnerabilities are not yet public and it is difficult to execute an attack using the flaws.