Most websites have at least one major security issue that could be exploited by cyber-criminals, according to a new survey.

Some 64 percent of 1,300 websites run by 250 enterprises have at least one serious vulnerability, said WhiteHat Security, which specialises in finding vulnerabilities in web applications. The statistics come from WhiteHat's customer base, which lets the company regularly review their sites for problems.

The most prevalent problem is cross-site scripting. There's a 66 percent a website will have such a problem, WhiteHat said. A cross-site scripting flaw can allow data or malicious code to be drawn from another a website, which can potentially cause a data breach.

Other common problems include information leakage issues, content spoofing, insufficient authorisation and SQL injection.

The danger of website application vulnerabilities is compound by the slowness with which companies attempt to fix them. If WhiteHat finds a vulnerability in a website, it informs the customer, said Jeremiah Grossman, WhiteHat's CTO.

In the case of a cross-site scripting problem, the fix is usually just one line of code, Grossman said. The problem in getting it fixed, however, tends to be on the human side.

WhiteHat will usually inform the security department of a company, which then has to pass on the information to the developers of the web application. The custom code of the web application can't be modified by the security department.

Management then has to give the OK for developers to work on fixing the code rather than creating revenue-generating features, which usually get priority, Grossman said. Sometimes, it's hard to quantify the risk of web-application vulnerabilities, which also muddies the waters for how fixing them is prioritised.

"A developer's job is to write code," Grossman said. "Security is not a priority when pushing out code."

Surprisingly, a lot of vulnerabilities take a lot time to be fixed, and some never get fixed. WhiteHat took a look at vulnerabilities that were found over a one-year period with its customers.

The company found it took an average of 67 days for a cross-site scripting problem to be fixed. That compared with 78 days for an information leakage problem, 87 days for content spoofing trouble and 62 days for a SQL injection vulnerability.

"What we can say with confidence is that IT security and development organisations must coordinate when it comes to dealing with website vulnerabilities to close the time-to-fix gap," the report said.

On average, only 30 percent to 60 percent of the vulnerabilities ever get fixed, Grossman said. The awareness of web-application problems "has never been higher but it needs to be a lot greater," he said.