Companies House WebFiling Security Issue Updates

Companies House Latest News

Published March 20th, 2026

Detected March 22nd, 2026

Summary

Companies House has issued guidance regarding a security issue discovered on March 13, 2026, affecting its WebFiling service. The issue potentially allowed logged-in users to access and alter other companies' details without consent. The agency has published this information to address user concerns and will provide further updates.

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What changed

Companies House has released guidance concerning a significant security vulnerability identified on March 13, 2026, within its WebFiling service. The vulnerability could have permitted unauthorized access and modification of other companies' registered details by logged-in users. This guidance serves to inform affected parties and address concerns arising from the incident, with the agency committing to further updates as the situation evolves.

Companies that rely on the WebFiling service should review the guidance to understand the nature of the security breach and any potential implications for their data. While no specific compliance actions are mandated in this guidance, users are advised to stay informed about subsequent updates from Companies House. The agency has apologized for the inconvenience and concern caused by this incident.

What to do next

Review Companies House guidance on the WebFiling security issue
Monitor for further updates from Companies House regarding the incident

Source document (simplified)

Guidance

WebFiling issue: information and updates

Information and ongoing updates about the Companies House WebFiling service issue discovered on 13 March 2026.

From: Companies House Published 20 March 2026 Get emails about this page

Documents

WebFiling issue: information and updates

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Details

On Friday 13 March 2026, Companies House was made aware of a security issue which meant that a logged-in registered user of our WebFiling service could potentially access and change another company’s details without their consent after performing a set of specific actions.

We recognise that this incident will have caused concern and inconvenience to many of the companies and individuals who rely on our services. We are sorry for that.

We’ve published this information and guidance for our users to address concerns. We’ll update this page as more information becomes available.