A libarchive security update has been released for Ubuntu Linux 20.04 LTS and 21.10.

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Ubuntu Security Notice USN-5291-1
February 17, 2022

libarchive vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.10
- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in libarchive.

Software Description:
- libarchive: Library to read/write archive files

Details:

It was discovered that libarchive incorrectly handled symlinks. If a
user or automated system were tricked into processing a specially crafted
archive, an attacker could possibly use this issue to change modes, times,
ACLs, and flags on arbitrary files. (CVE-2021-23177, CVE-2021-31566)

It was discovered that libarchive incorrectly handled certain RAR archives.
If a user or automated system were tricked into processing a specially
crafted RAR archive, an attacker could use this issue to cause libarchive
to crash, resulting in a denial of service, or possibly execute arbitrary
code. (CVE-2021-36976)

Update instructions:

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

Ubuntu 21.10:
libarchive13 3.4.3-2ubuntu0.1

Ubuntu 20.04 LTS:
libarchive13 3.4.0-2ubuntu1.1

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

References:
  https://ubuntu.com/security/notices/USN-5291-1
CVE-2021-23177, CVE-2021-31566, CVE-2021-36976

Package Information:
  https://launchpad.net/ubuntu/+source/libarchive/3.4.3-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/libarchive/3.4.0-2ubuntu1.1