Oracle has released a major security update for the version of Java programming language that runs inside Web browsers.
The patch fixes 42 vulnerabilities within Java, including "the vast majority" of those that have been rated as the most critical, said Oracle Executive Vice President Hasan Rizvi.
A series of big security flaws in the Java plug-in for browsers have been uncovered in the past year by researchers and hackers, and some have been used by criminal groups before previous patches were issued.
One widespread hacking campaign disclosed this year infected computers using Microsoft's Windows and Apple software inside hundreds of companies, including Facebook, Apple and Twitter.
The situation grew so bad earlier this year that the U.S. Department of Homeland Security recommended that computer users disable Java in the browser.
But many large companies use internal software that relies on Java and have been pressing Oracle to make the language safer.
Perhaps the most significant change will be that, in the default setting, sites will not be able to force the small programs known as Java applets to run in the browser unless they have been digitally signed. Users can override that only if they click to acknowledge the risk, Rizvi said.
Not all known problems are being fixed with the current patch, but there are no unpatched problems that are being actively exploited, Rizvi said.
Primarily a database software and applications company, Oracle inherited Java when it bought Sun Microsystems in 2010.
It is the company's greatest exposure to the mass market, as versions of Java run on desktops, in telephones and other devices and on servers.
The browser version, however, has been especially prone to security problems.
Last year, Java surpassed Adobe's Reader software as the most frequently attacked piece of software, according to security software maker Kaspersky Lab.
Java was the vehicle for 50 per cent of all cyber attacks last year in which hackers broke into computers by exploiting software bugs, according to Kaspersky.
That was followed by Adobe Reader, which was involved in 28 per cent of all incidents.
Microsoft Windows and Internet Explorer were involved in about 3 per cent of incidents, according to the survey.
Although no high-profile Oracle customers have publicly threatened to desert the company over security issues, Rizvi acknowledge widespread concern.
"It was pretty embarrassing what happened with the Facebook attacks," said IDC analyst Al Hilwa.
"It's a fight for the Java plug-in's life. Either a lot of companies are going to turn these off, or they are going to have their confidence restored."