Comodo Advisory - 'Heartbleed' vulnerability in OpenSSL

  • All customers are advised to patch systems to run the latest version of OpenSSL
  • Vulnerability lies with OpenSSL, not with Comodo certificates or Comodo CA keys
  • Certificates on affected systems need to be replaced, free of charge, with immediate effect
  • Customers can order a certificate reissue via our web-interface, management portal or the APIs. Contact if help is required.

In light of the recently discovered vulnerability known as 'Heartbleed', Comodo CA, a leading Certificate Authority and Internet security organization, would like to advise customers to patch OpenSSL to the latest version and would like to confirm that the vulnerability lies with the OpenSSL software and not with Comodo certificates or Comodo CA keys. Comodo will work with customers, partners, platform vendors and service providers to help ensure affected parties are made fully aware of the issue over the coming days, that customer systems are updated with the fixed version of OpenSSL, and that customers can quickly and easily acquire a certificate reissuance that may be required as a result of patching OpenSSL.

What is the 'Heartbleed' vulnerability?

On Tuesday 8th of April 2014, a serious vulnerability to OpenSSL known as 'Heartbleed' was made public by a team of researchers.

The 'Heartbleed' vulnerability means that it is possible for an attacker to silently 'steal' private keys for SSL certificates, as well as other secret information, on affected versions of OpenSSL.

OpenSSL is an incredibly popular cryptographic software library, and provides SSL/TLS communication for large numbers of applications. The bug causing the vulnerability was introduced to OpenSSL in December 2011 and has been 'in the wild' since the release of OpenSSL 1.0.1 on March 14th 2012. However, it was only discovered within the past day and, other than a proof of concept, Comodo is not aware of any real-world exploits at this point in time.

Full details of the vulnerability, including more technical details, can be found at:

What is affected?

OpenSSL versions affected: 1.0.1 through to 1.0.1f (inclusive).

The following OpenSSL versions are NOT affected:


1.0.0 (entire branch)

0.9.8 (entire branch)

The release of OpenSSL 1.0.1g on the 7th April 2014 fixes the bug.

How do I fix it?

Any systems using vulnerable versions of OpenSSL need to be patched or updated.

OpenSSL themselves have released a patch, and many other software vendors have updated their software as well.

Please contact your vendor for further details.

Patch your server before you install your new certificate. If you put a new certificate onto a vulnerable server you risk compromising the key of the new certificate.

Is my site affected?

Customers can test whether they are affected by visiting to verify the presence of this vulnerability.

What about my certificates?

Because there is a theoretical possibility that Heartbleed could already have been exploited, Comodo must replace certificates on systems running the affected OpenSSL version. Certificates on affected systems should be replaced, as soon as possible and the previous certificates should be revoked.

Comodo have ensured that all of our own websites using OpenSSL have been patched and updated, and we have also reissued certificates for those sites as a precautionary measure. We know it is a big task that you did not ask for, but like any other web-server vulnerability it requires your urgent attention.

Comodo, unlike other CAs, has a no-charge reissue policy - so replacing your certificate and maintaining the security of your website and your systems is simple and incurs no additional cost.

To perform a reissue, please follow the normal procedures - reissuing via our web-interface, management portal or the APIs.

Visit Comodo SSL Reviews page to compare features of various ssl certificates from comodo.

Should you need any additional assistance, please contact: or submit a ticket to:


Posted: 04/08/2014.