CVE-2026-40199

Name	CVE-2026-40199
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libnet-cidr-lite-perl (PTS)	bullseye	0.22-1	vulnerable
	forky, bookworm, trixie	0.22-2	vulnerable
	sid	0.22-3	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libnet-cidr-lite-perl	source	(unstable)	0.22-3

Notes

[trixie] - libnet-cidr-lite-perl <no-dsa> (Minor issue, will be fixed via point release)
[bookworm] - libnet-cidr-lite-perl <no-dsa> (Minor issue, will be fixed via point release)
https://lists.security.metacpan.org/cve-announce/msg/38785618/
Fixed by: https://github.com/stigtsp/Net-CIDR-Lite/commit/b7166b1fa17b3b14b4c795ace5b3fbf71a0bd04a (0.23)
Tests: https://github.com/stigtsp/Net-CIDR-Lite/commit/029b9417d2078827f790addfa1dceb1df8297b85 (0.23)