A commons-io security update has been released for Debian GNU/Linux 9 LTS to address a path traversal vulnerability.

DLA 2741-1: commons-io security update

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Debian LTS Advisory DLA-2741-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Markus Koschany
August 12, 2021   https://wiki.debian.org/LTS
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Package : commons-io
Version : 2.5-1+deb9u1
CVE ID : CVE-2021-29425

Lukas Euler discovered a path traversal vulnerability in commons-io, a Java
library for common useful IO related classes. When invoking the method
FileNameUtils.normalize with an improper input string, like "//../foo", or
"\\..\foo", the result would be the same value, thus possibly providing access
to files in the parent directory, but not further above (thus "limited" path
traversal), if the calling code would use the result to construct a path value.

For Debian 9 stretch, this problem has been fixed in version
2.5-1+deb9u1.

We recommend that you upgrade your commons-io packages.

For the detailed security status of commons-io please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/commons-io

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://wiki.debian.org/LTS