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Security Advisory

USN-4233-2: GnuTLS update

USN-4233-2: GnuTLS update




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 16.04
  • Canonical Ubuntu 18.04


USN-4233-1 disabled SHA1 being used for digital signature operations in GnuTLS. In certain network environments, certificates using SHA1 may still be in use. This update adds the %VERIFY_ALLOW_BROKEN and %VERIFY_ALLOW_SIGN_WITH_SHA1 priority strings that can be used to temporarily re-enable SHA1 until certificates can be replaced with a stronger algorithm. Original advisory details: As a security improvement, this update marks SHA1 as being untrusted for digital signature operations.

Affected Cloud Foundry Products and Versions

Severity is unknown unless otherwise noted.

  • Xenial Stemcells
    • 621.x versions prior to 621.55
    • 456.x versions prior to 456.96
    • 315.x versions prior to 315.167
    • 250.x versions prior to 250.181
    • 170.x versions prior to 170.201
    • 97.x versions prior to 97.230
    • All other stemcells not listed.
  • cflinuxfs3
    • All versions prior to 0.157.0
  • CF Deployment
    • All versions prior to v12.29.0


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

  • Xenial Stemcells
    • Upgrade 621.x versions to 621.55 or greater
    • Upgrade 456.x versions to 456.96 or greater
    • Upgrade 315.x versions to 315.167 or greater
    • Upgrade 250.x versions to 250.181 or greater
    • Upgrade 170.x versions to 170.201 or greater
    • Upgrade 97.x versions to 97.230 or greater
    • All other stemcells should be upgraded to the latest version available on
  • cflinuxfs3
    • Upgrade all versions to 0.157.0 or greater
  • CF Deployment
    • Upgrade all versions to v12.29.0 or greater


2020-01-23: Initial vulnerability report published.

Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR