Number: AV20-053
Date: 04 March 2020
On 3 March 2020 Let’s Encrypt announced that they would be revoking 3,048,289 TLS/SSL certificates on 4 March 2020 at 3:00pm EST. The revocation was triggered by the discovery of a vulnerability in some certificates that would allow possible forged certificates to be issued under specific circumstances. Let’s Encrypt is attempting to contact all registered owners of affected certificates through the contact information which was provided to Let’s Encrypt upon registration. The number of certificates being revoked represents 2.6% of all certificates. Upon certificate revocation, an affected web site may become inaccessible to web browsers or may cause the web browser to display a security caution message.
The Cyber Centre recommends that all users of Let’s Encrypt TLS/SSL certificates renew their certificates as soon as possible, whether or not Let’s Encrypt has advised them of an issue with their individual certificate. For additional information, including tools to test if a certificate is affected, please refer to Let’s Encrypt’s official security advice:
https://community.letsencrypt.org/t/revoking-certain-certificates-on-march-4/114864
Note to Readers
The Canadian Centre for Cyber Security (Cyber Centre) operates as part of the Communications Security Establishment. We are Canada’s national authority on cyber security and we lead the government’s response to cyber security events. As Canada's national computer security incident response team, the Cyber Centre works in close collaboration with government departments, critical infrastructure, Canadian businesses and international partners to prepare for, respond to, mitigate, and recover from cyber events. We do this by providing authoritative advice and support, and coordinating information sharing and incident response. The Cyber Centre is outward-facing, welcoming partnerships that help build a stronger, more resilient cyber space in Canada.