Cloud Foundry Logo
blog single gear
Security Advisory

USN-4635-1: Kerberos vulnerability




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 14.04
  • Canonical Ubuntu 16.04
  • Canonical Ubuntu 18.04


Demi Obenour discovered that Kerberos incorrectly handled certain ASN.1. An attacker could possibly use this issue to cause a denial of service.

CVEs contained in this USN include: CVE-2020-28196.

Affected Cloud Foundry Products and Versions

Severity is medium unless otherwise noted.

  • cflinuxfs3
    • All versions prior to 0.211.0
  • Xenial Stemcells
    • 315.x versions prior to 315.202
    • 456.x versions prior to 456.129
    • 621.x versions prior to 621.93
    • All other stemcells not listed.
  • CF Deployment
    • All versions prior to 15.4.0


Users of affected products are strongly encouraged to follow the mitigations below. The Cloud Foundry project recommends upgrading the following releases:

  • cflinuxfs3
    • Upgrade All versions to 0.211.0 or greater
  • Xenial Stemcells
    • Upgrade 315.x versions to 315.202 or greater
    • Upgrade 456.x versions to 456.129 or greater
    • Upgrade 621.x versions to 621.93 or greater
    • All other stemcells should be upgraded to the latest version available on
  • CF Deployment
    • Upgrade All versions to 15.4.0 or greater


2021-01-13: Initial vulnerability report published.

Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR