UBUNTU-CVE-2021-4456

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Source
https://ubuntu.com/security/CVE-2021-4456
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2021-4456
Upstream
Downstream
Related
Published
2026-02-27T01:16:00Z
Modified
2026-03-20T06:36:38Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Net::CIDR versions before 0.24 for Perl mishandle leading zeros in IP CIDR addresses, which may have unspecified impact. The functions addr2cidr and cidrlookup may return leading zeros in a CIDR string, which may in turn be parsed as octal numbers by subsequent users. In some cases an attacker may be able to leverage this to bypass access controls based on IP addresses. The documentation advises validating untrusted CIDR strings with the cidrvalidate function. However, this mitigation is optional and not enforced by default. In practice, users may call addr2cidr or cidrlookup with untrusted input and without validation, incorrectly assuming that this is safe.

References

Affected packages

Ubuntu:22.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.21-1ubuntu0.2?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.21-1ubuntu0.2

Affected versions

0.*
0.20-1
0.21-1

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.21-1ubuntu0.2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"
Ubuntu:24.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.21-2ubuntu0.2?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.21-2ubuntu0.2

Affected versions

0.*
0.21-2

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.21-2ubuntu0.2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"
Ubuntu:Pro:14.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.17-1ubuntu0.14.04.1~esm2?arch=source&distro=esm-infra-legacy/trusty

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.17-1ubuntu0.14.04.1~esm2

Affected versions

0.*
0.17-1

Ecosystem specific 

{
    "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.17-1ubuntu0.14.04.1~esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"
Ubuntu:Pro:16.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.17-1ubuntu0.16.04.1~esm2?arch=source&distro=esm-infra/xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.17-1ubuntu0.16.04.1~esm2

Affected versions

0.*
0.17-1

Ecosystem specific 

{
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.17-1ubuntu0.16.04.1~esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"
Ubuntu:Pro:18.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.18-1ubuntu0.1~esm2?arch=source&distro=esm-infra/bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.18-1ubuntu0.1~esm2

Affected versions

0.*
0.18-1

Ecosystem specific 

{
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.18-1ubuntu0.1~esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"
Ubuntu:Pro:20.04:LTS
libnet-cidr-perl

Package

Name
libnet-cidr-perl
Purl
pkg:deb/ubuntu/libnet-cidr-perl@0.20-1ubuntu0.1~esm2?arch=source&distro=esm-infra/focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.20-1ubuntu0.1~esm2

Affected versions

0.*
0.20-1

Ecosystem specific 

{
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "libnet-cidr-perl",
            "binary_version": "0.20-1ubuntu0.1~esm2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-4456.json"