CPANSA-Net-CIDR-Lite-2026-40199: Net-CIDR-Lite vulnerability

Publisher giterlizzi Document category csaf_security_advisory
Initial release date 2026-04-10T00:00:00 Engine CSAF Perl Toolkit 0.26
Current release date 2026-04-10T00:00:00 Build Date
Current version 1 Status final
CVSS v3.1 Base Score 6.5 Severity
Original language Language en
Also referred to

Vulnerability Description

Net::CIDR::Lite versions before 0.23 for Perl mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass. _pack_ipv6() includes the sentinel byte from _pack_ipv4() when building the packed representation of IPv4 mapped addresses like ::ffff:192.168.1.1. This produces an 18 byte value instead of 17 bytes, misaligning the IPv4 part of the address. The wrong length causes incorrect results in mask operations (bitwise AND truncates to the shorter operand) and in find() / bin_find() which use Perl string comparison (lt/gt). This can cause find() to incorrectly match or miss addresses. Example: my $cidr = Net::CIDR::Lite->new("::ffff:192.168.1.0/120"); $cidr->find("::ffff:192.168.2.0"); # incorrectly returns true This is triggered by valid RFC 4291 IPv4 mapped addresses (::ffff:x.x.x.x). See also CVE-2026-40198, a related issue in the same function affecting malformed IPv6 addresses.

Vulnerabilities

CVE-2026-40199

Vulnerability Description

Net::CIDR::Lite versions before 0.23 for Perl mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass.

_pack_ipv6() includes the sentinel byte from _pack_ipv4() when building the packed representation of IPv4 mapped addresses like ::ffff:192.168.1.1. This produces an 18 byte value instead of 17 bytes, misaligning the IPv4 part of the address.

The wrong length causes incorrect results in mask operations (bitwise AND truncates to the shorter operand) and in find() / bin_find() which use Perl string comparison (lt/gt). This can cause find() to incorrectly match or miss addresses.

Example:

my $cidr = Net::CIDR::Lite->new("::ffff:192.168.1.0/120");
$cidr->find("::ffff:192.168.2.0"); # incorrectly returns true

This is triggered by valid RFC 4291 IPv4 mapped addresses (::ffff:x.x.x.x).

See also CVE-2026-40198, a related issue in the same function affecting malformed IPv6 addresses.

Weakness CWE-130 : Improper Handling of Length Parameter Inconsistency

Product status

Known affected
Product Score
Net-CIDR-Lite less than 0.23
CVSS Version CVSS Vector CVSS Base Score CVSS Base Severity
3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N 6.5 Medium
Fixed

giterlizzi

Namespace: https://github.com/giterlizzi/

gdt@cpan.org

References

Revision history

Version Date of the revision Summary of the revision
1 Fri Apr 10 00:00:00 2026 First release

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