A breach at Mumsnet, a website geared toward parents, could have caused users logging in at the same time to have their account information switched.

“We believe that a software change, as part of moving our services to the cloud, that was put in place on Tuesday p.m. was the cause of this issue,” a Mumset forum moderator posted Thursday, noting that users signing in between 2 p.m. on Feb. 5 and 9 a.m. on Feb. 7 were vulnerable.

Mumsnet was alerted to the issue Wednesday night by a user who logged in and saw another user’s account information. The site reversed the software change Thursday morning.

“This was certainly a failure of IT operations and this should not have occurred, but all change is risky and there is no such thing as perfect security,” said Thomas Owen, head of security and business services at Mumset. “Disruptive changes are a vulnerable time for organizations and comprehensive testing is vital to mitigate against risks of failure, but after a certain point it suffers from the law of diminishing returns.”

But Owen commended the site’s response to the breach. “While Mumsnet’s change management processes might have been lacking, they have demonstrated great incident management so far in this situation,” he said. “Mumsnet appear to have discovered the error, rapidly fixed it, reported it to the regulator and then gone public with a frank and detailed explanation. It’s handy that best practice in incident management is now also legally enforced under DPA 2018.”