user accounts hijacked, and its CEO was impersonated as part of the Heartbleed exploit. The site later published an explanation of the incident saying it was due to Heartbleed and the vulnerability was fixed.

In February 2025, child sexual abuse photos were posted on the forums and remained visible for several hours, as no Mumsnet staff were available, as the management team relied on "volunteer" moderators to patrol the forums outside of standard office hours. This led to a temporary ban on images