CVE-2026-40198 Affecting libnet-cidr-lite-perl package, versions *


Severity

Recommended
low

Based on Debian security rating.

Threat Intelligence

EPSS
0.31% (24th percentile)

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  • Snyk IDSNYK-DEBIAN11-LIBNETCIDRLITEPERL-16031157
  • published14 Apr 2026
  • disclosed10 Apr 2026

Introduced: 10 Apr 2026

CVE-2026-40198  (opens in a new tab)

How to fix?

There is no fixed version for Debian:11 libnet-cidr-lite-perl.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libnet-cidr-lite-perl package and not the libnet-cidr-lite-perl package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

Net::CIDR::Lite versions before 0.23 for Perl does not validate IPv6 group count, which may allow IP ACL bypass.

_pack_ipv6() does not check that uncompressed IPv6 addresses (without ::) have exactly 8 hex groups. Inputs like "abcd", "1:2:3", or "1:2:3:4:5:6:7" are accepted and produce packed values of wrong length (3, 7, or 15 bytes instead of 17).

The packed values are used internally for mask and comparison operations. find() and bin_find() use Perl string comparison (lt/gt) on these values, and comparing strings of different lengths gives wrong results. This can cause find() to incorrectly report an address as inside or outside a range.

Example:

my $cidr = Net::CIDR::Lite->new("::/8"); $cidr->find("1:2:3"); # invalid input, incorrectly returns true

This is the same class of input validation issue as CVE-2021-47154 (IPv4 leading zeros) previously fixed in this module.

See also CVE-2026-40199, a related issue in the same function affecting IPv4 mapped IPv6 addresses.

CVSS Base Scores

version 3.1