But users of the popular compression tool will need to upgrade to version 9 of the software.
WinZip Computing warned last month of a flaw in WinZip, its tool for compressing and decompressing files that runs on the Windows operating system. WinZip versions 3.x, 6.x, 7.x, 8.x and 9.x contain vulnerabilities that could allow a remote attacker to execute malicious code and cause a buffer overflow.
The problem is caused by a flaw in the way WinZip handles command line inputs. Security software company Secunia has just rated the flaw "highly critical," the fourth highest out of its five severity levels.
WinZip has released a patch for version 9 of the software.
The fix is contained in WinZip 9.0 Service Release 1. That update also gives the software the capability to issue warning messages for some problems. For example, if a user double-clicks on an .exe file compressed within a Zip file, WinZip will warn that the compressed file could contain a virus.
The company recommends on its Web site that all users upgrade to version 9 to get the fix at no cost. For new users, a free evaluation version of the patch is available, but after 21 days, they would need to pay the $29 license fee for WinZip.
The company said it was not aware of the vulnerability having been exploited in the wild when it released the patch.
This news comes only a couple of weeks after warnings that a flaw in Winamp, a media application that runs on Windows, has been exploited to infect people's computers with spyware. When Secunia released the initial advisory, no patch was available, and the company suggested that users switch to another product.
The flaw has now been patched, and the latest Secunia advisory, updated Monday, tells users to upgrade to Winamp 5.05.
Ingrid Marson of ZDNet UK reported from London.