Ubuntu 26.04 LTS Net--CIDR--Lite Critical Access Bypass CVE-2021-47154

ubuntu

June 8, 2026

Several security issues were fixed in Net::CIDR::Lite.

Summary

Several security issues were fixed in Net::CIDR::Lite.

Software Description:

- libnet-cidr-lite-perl: module for merging IPv4 or IPv6 CIDR address ranges

Details:

Dave Rolsky discovered that Net::CIDR::Lite did not properly handle

extraneous zero characters at the beginning of an IP address string. A

remote attacker could possibly use this issue to bypass access controls

that are based on IP addresses. This issue only affected Ubuntu 16.04 LTS

and Ubuntu 18.04 LTS. (CVE-2021-47154)

It was discovered that Net::CIDR::Lite did not properly validate the IPv6

group count when handling uncompressed IPv6 addresses. A remote attacker

could possibly use this issue to bypass access controls. (CVE-2026-40198)

It was discovered that Net::CIDR::Lite mishandled IPv4 mapped IPv6

addresses. A remote attacker could possibly use this issue to bypass access

controls that are based on IP addresses. (CVE-2026-40199)

Topics Covered

security advisory critical Ubuntu authentication bypass Net-CIDR-Lite CVE-2021-47154

Update Instructions

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

Ubuntu 26.04 LTS
  libnet-cidr-lite-perl           0.22-2ubuntu0.26.04.1

Ubuntu 25.10
  libnet-cidr-lite-perl           0.22-2ubuntu0.25.10.1

Ubuntu 24.04 LTS
  libnet-cidr-lite-perl           0.22-2ubuntu0.24.04.1

Ubuntu 22.04 LTS
  libnet-cidr-lite-perl           0.22-1ubuntu0.1

Ubuntu 20.04 LTS
  libnet-cidr-lite-perl           0.21-2ubuntu0.1+esm1
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  libnet-cidr-lite-perl           0.21-1ubuntu0.18.04.1~esm1
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  libnet-cidr-lite-perl           0.21-1ubuntu0.16.04.1~esm1
                                  Available with Ubuntu Pro

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