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Security Advisory

USN-5745-2: shadow regression



USN-5745-2: shadow regression




Canonical Ubuntu

Versions Affected

  • Canonical Ubuntu 16.04
  • Canonical Ubuntu 18.04


USN-5745-1 fixed vulnerabilities in shadow. Unfortunately that update introduced a regression that caused useradd to behave incorrectly in Ubuntu 14.04 ESM, Ubuntu 16.04 ESM, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. This update reverts the security fix pending further investigation. We apologize for the inconvenience. Original advisory details: Florian Weimer discovered that shadow was not properly copying and removing user directory trees, which could lead to a race condition. A local attacker could possibly use this issue to setup a symlink attack and alter or remove directories without authorization. Update Instructions: Run `sudo pro fix USN-5745-2` to fix the vulnerability. The problem can be corrected by updating your system to the following package versions: passwd – 1:4.2-3.1ubuntu5.5+esm3 login – 1:4.2-3.1ubuntu5.5+esm3 uidmap – 1:4.2-3.1ubuntu5.5+esm3 Available with Ubuntu Pro (Infra-only):

Affected Cloud Foundry Products and Versions

Severity is unknown unless otherwise noted.

  • Bionic Stemcells
    • 1.x versions prior to 1.161
    • All other stemcells not listed.
  • cflinuxfs3
    • All versions prior to 0.342.0
  • CF Deployment
    • All versions prior to 24.0.0, or later versions with Bionic Stemcells prior to 1.161 or Xenial Stemcells prior to 621.359


Users of affected products are strongly encouraged to follow the mitigations below.

The Cloud Foundry project recommends upgrading the following releases:

  • Bionic Stemcells
    • Upgrade 1.x versions to 1.161 or greater
    • All other stemcells should be upgraded to the latest version available on
  • cflinuxfs3
    • Upgrade all versions to 0.342.0 or greater
  • CF Deployment
    • Upgrade all versions to 24.0.0 or greater, upgrade Bionic Stemcells to 1.161 or greater, and upgrade Xenial Stemcells to 621.359 or greater



2023-01-12: Initial vulnerability report published.

Cloud Foundry Foundation Security Team Profile Image

Cloud Foundry Foundation Security Team, AUTHOR