1. Ubuntu Security Notices
  2. USN-5745-2

USN-5745-2: shadow regression

Publication date

29 November 2022

Overview

USN-5745-1 introduced a regression in shadow.

Releases

Packages

Details

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.

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

In general, a standard system update will make all the necessary changes.

Learn more about how to get the fixes.

The problem can be corrected by updating your system to the following package versions:

Ubuntu Release Package Version
20.04 focal passwd –  1:4.8.1-1ubuntu5.20.04.4
login –  1:4.8.1-1ubuntu5.20.04.4
uidmap –  1:4.8.1-1ubuntu5.20.04.4
18.04 bionic passwd –  1:4.5-1ubuntu2.5
login –  1:4.5-1ubuntu2.5
uidmap –  1:4.5-1ubuntu2.5
16.04 xenial passwd –  1:4.2-3.1ubuntu5.5+esm3  
login –  1:4.2-3.1ubuntu5.5+esm3  
uidmap –  1:4.2-3.1ubuntu5.5+esm3  
14.04 trusty passwd –  1:4.1.5.1-1ubuntu9.5+esm3  
login –  1:4.1.5.1-1ubuntu9.5+esm3  
uidmap –  1:4.1.5.1-1ubuntu9.5+esm3  

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References

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