Companies House Data Breach

18 Mar 2026

Companies House has been made aware of a security issue which meant that a logged-in user of their WebFiling service could potentially access and change some elements of another company's details without their consent after performing a specific set of actions.

The investigation carried out by Companies House has established that specific data from individual companies not normally published on the Companies House register may have been visible to other logged-in WebFiling users. This includes dates of birth, residential addresses and company email addresses. It may also have been possible for unauthorised filings — such as accounts or changes of director — to have been made on another company's record.

Companies House have also confirmed that passwords were not compromised.

Next Steps

Companies House has advised all companies listed on the Companies House register to check their registered details and filing history to make sure everything appears correct. If a company has a concern, please contact Companies House via email at enquiries@companieshouse.gov.uk using 'WebFiling issue' in the subject heading and include evidence to describe the concern.

You can view the full message from Companies House here.

Author

Melanie O'Connor | ATT | CTA
Director