Third-party taxi booking apps have become very popular. But a recent report suggests they often contain bugs, especially the unofficial versions available on many websites.

Online security website WooYun.org says nine popular taxi booking apps have issues with security bugs. They include the largest booking apps, Didi Taxi and Uber. The report says the bugs could cause the leak of private user information. But Didi says it has already updated the app to fix the problems.

"The seven bugs they found didn't mean we have seven bugs right now. They are the seven bugs which were successively found over the past three years. We know that any Internet product and any software will have bugs. And actually, every time a bug was reported, we repaired it. Also, only one out of those seven bugs is related to users' information," Ye Yun with Didi Taxi said.

But the report has some people wondering if the apps are safe to use.

"I don't use these apps often. I saw once there was information sold on Taobao, 100 pieces of information sells for only about five yuan," Shanghai resident Li Qian said.

"Most personal information is transparent rather than concealed. It is rather public. In other words, your personal information will not be concealed. Such problems also happen in many bank accounts," Shanghai resident Sun Xue said.

We talked to an international security company with an office in Shanghai today. It has analyzed more than 17 million apps over the past 11 years. It lists both Did and Uber apps in the medium security level, meaning they are generally safe to use. But one expert warns about using modified versions of the apps, which are easily available online.

"Some users didn't download official apps, as some apps on the market are duplicated. For example, one may add some advertisements inside Didi Taxi app, and then launch it on the market. That may pick up some bug during the process. So sometimes it's not the problem of Didi Taxi's official apps, but some others," Liu ZHengping, Sr. Manager with TS Engineering of Trend Micro, said.

Liu says nearly half of the apps it tests contain some type of malware. The biggest problems involve gaming and banking apps.

Internet security experts suggest users download apps from official websites. They say users of android systems or jailbroken phones need to pay special attention.