6 May 2022

Corero Network Security plc

("Corero" or the "Company")

Block Listing Application

Corero Network Security plc (AIM: CNS), a leading provider of real-time, high-performance, automatic Distributed Denial of Service (DDoS) cyber defense solutions, announces that an application has been made to the London Stock Exchange for a block listing of 61,856,538 new ordinary shares of 1 pence each in the Company ("Ordinary Shares").

These Ordinary Shares will be issued from time to time in order to satisfy the requirement to allot shares under the Corero Network Security plc Unapproved Share Options Plan, the Enterprise Management Incentive (EMI) Plan and the Executive Enterprise Management Incentive (EMI) Plan (collectively the "Employee Share Schemes").

It is expected that admission will become effective on 12 May 2022. The Ordinary Shares under the block listing will rank pari passu with the Company's existing Ordinary Shares.

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About Corero Network Security

Corero Network Security plc is a global leader in real-time, high-performance, automatic DDoS cyber defense solutions. Both Service and Hosting providers, alongside digital enterprises across the globe rely on Corero's award winning cybersecurity technology to eliminate the threat of Distributed Denial of Service (DDoS) to their digital environment through automatic attack detection and mitigation, coupled with network visibility, analytics and reporting. Corero's industry leading SmartWall and SecureWatch technology provides scalable protection capabilities against external DDoS attackers and internal DDoS botnets in the most complex edge and subscriber environments, while enabling a more cost-effective economic model than previously available. Corero's key operational centers located in Marlborough, Massachusetts, USA and Edinburgh, UK, with the Company's headquarters in Amersham, UK. The Company is listed on the London Stock Exchange's AIM market under the ticker CNS.  For more information, visit       www.corero.com