One in five Windows applications is not patched, according to Danish security firm Secunia.
The company said that more than a fifth of the applications scanned by its Personal Software Inspector (PSI) utility were open to attack because available fixes for security flaws had not been applied.
"More than 20 percent of all applications installed on users' PCs have known security flaws, but the users have yet to install the patch provided by the vendor of [the] product," said Jakob Balle, Secunia's development manager, on on Secunia's blog.
The 20 percentfigure was based on scans of more than 14.5 million applications installed on the Windows PCs operated by users who downloaded and installed Secunia's PSI. The utility scans for some 4,200 different applications and reports on their patch status.
The 1-in-5 ratio, however, is an improvement over earlier PSI scans. Last May Secunia said that 28 percent of the applications PSI scanned were missing available security updates.
Secunia released the free patch-detection utility a year ago but shifted it to Release Candidate 1 (RC1) stage earlier this month. The company claimed that nearly 191,000 users have downloaded and run the program.