A TCMU security update has been released Ubuntu Linux 20.04 LTS and 20.10.

USN-4707-1: TCMU vulnerability

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Ubuntu Security Notice USN-4707-1
January 28, 2021

tcmu vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS

Summary:

tcmu could be made to crash if it received specially crafted
input.

Software Description:
- tcmu: TCM-Userspace backend

Details:

It was discovered that TCMU lacked a check for transport-layer restrictions,
allowing remote attackers to read or write files via directory traversal in
an XCOPY request.

Update instructions:

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

Ubuntu 20.10:
libtcmu2 1.5.2-5ubuntu0.20.10.1
tcmu-runner 1.5.2-5ubuntu0.20.10.1

Ubuntu 20.04 LTS:
libtcmu2 1.5.2-5ubuntu0.20.04.1
tcmu-runner 1.5.2-5ubuntu0.20.04.1

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

References:
  https://usn.ubuntu.com/4707-1
CVE-2021-3139

Package Information:
  https://launchpad.net/ubuntu/+source/tcmu/1.5.2-5ubuntu0.20.10.1
  https://launchpad.net/ubuntu/+source/tcmu/1.5.2-5ubuntu0.20.04.1