A ruby2.3 security update has been released for Debian GNU/Linux 9 LTS to address multiple vulnerabilities.

DLA 2780-1: ruby2.3 security update

- ----------------------------------------------------------------------
Debian LTS Advisory DLA-2780-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Utkarsh Gupta
October 11, 2021   https://wiki.debian.org/LTS
- ----------------------------------------------------------------------

Package : ruby2.3
Version : 2.3.3-1+deb9u10
CVE ID : CVE-2021-31799 CVE-2021-31810 CVE-2021-32066
Debian Bug : 990815

Multiple vulnerabilites in ruby2.3, interpreter of object-oriented
scripting language Ruby, were discovered.

CVE-2021-31799

In RDoc 3.11 through 6.x before 6.3.1, as distributed with
Ruby through 2.3.3, it is possible to execute arbitrary
code via | and tags in a filename.

CVE-2021-31810

An issue was discovered in Ruby through 2.3.3. A malicious
FTP server can use the PASV response to trick Net::FTP into
connecting back to a given IP address and port. This
potentially makes curl extract information about services
that are otherwise private and not disclosed (e.g., the
attacker can conduct port scans and service banner extractions).

CVE-2021-32066

An issue was discovered in Ruby through 2.3.3. Net::IMAP does
not raise an exception when StartTLS fails with an an unknown
response, which might allow man-in-the-middle attackers to
bypass the TLS protections by leveraging a network position
between the client and the registry to block the StartTLS
command, aka a "StartTLS stripping attack."

For Debian 9 stretch, these problems have been fixed in version
2.3.3-1+deb9u10.

We recommend that you upgrade your ruby2.3 packages.

For the detailed security status of ruby2.3 please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/ruby2.3

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