A LZ4 security update has been released for Ubuntu Linux 18.04, 20.04 LTS, 20.10, and 21.04.

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Ubuntu Security Notice USN-4968-1
May 26, 2021

lz4 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

LZ4 could be made to crash or run programs if it opened a specially crafted
file.

Software Description:
- lz4: Extremely fast compression algorithm

Details:

It was discovered that LZ4 incorrectly handled certain memory operations.
If a user or automated system were tricked into uncompressing a specially-
crafted LZ4 file, a remote attacker could use this issue to cause LZ4 to
crash, resulting in a denial of service, or possibly execute arbitrary
code.

Update instructions:

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

Ubuntu 21.04:
liblz4-1 1.9.3-1ubuntu0.1

Ubuntu 20.10:
liblz4-1 1.9.2-2ubuntu0.20.10.1

Ubuntu 20.04 LTS:
liblz4-1 1.9.2-2ubuntu0.20.04.1

Ubuntu 18.04 LTS:
liblz4-1 0.0~r131-2ubuntu3.1

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

References:
  https://ubuntu.com/security/notices/USN-4968-1
CVE-2021-3520

Package Information:
  https://launchpad.net/ubuntu/+source/lz4/1.9.3-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/lz4/1.9.2-2ubuntu0.20.10.1
  https://launchpad.net/ubuntu/+source/lz4/1.9.2-2ubuntu0.20.04.1
  https://launchpad.net/ubuntu/+source/lz4/0.0~r131-2ubuntu3.1