Google researchers found a vulnerability with Apple's Safari browser.
The tech giant's browser had a flaw with a feature designed to protect users' privacy but also created vulnerabilities which put data and privacy at risk.
In a paper published this week, a group of security engineers at Google disclosed a number of flaws which would've let potential hackers view browsing and search history, while also letting websites track your internet behaviour.
In a statement, Google said: "We've long worked with companies across the industry to exchange information about potential vulnerabilities and protect our respective users.
"Our core security research team has worked closely and collaboratively with Apple on this issue. The technical paper simply explains what our researchers discovered so others can benefit from their findings."
The feature in question is Safari's Intelligent Tracking Prevention (ITP) - first launched in 2017 - which was designed to protect users from third-party cookies by logging their use and blocking sites from using them.
However, Google's paper claims logging this information basically gave potential attackers a way to access a detailed view of someone's web history.
Although Apple have declined to comment, the company insisted it previously addressed the problem and in December they credited Google for finding the vulnerabilities.
John Wilander - Apple's WebKit engineer behind the ITP tool - wrote at the time: "We'd like to thank Google for sending us a report in which they explore both the ability to detect when web content is treated differently by tracking prevention and the bad things that are possible with such detection."