CVE-2026-40198

Publication date 10 April 2026

Last updated 8 June 2026

Ubuntu priority

Cvss 3 Severity Score

Description

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libnet-cidr-lite-perl	26.04 LTS resolute	Fixed 0.22-2ubuntu0.26.04.1
	25.10 questing	Fixed 0.22-2ubuntu0.25.10.1
	24.04 LTS noble	Fixed 0.22-2ubuntu0.24.04.1
	22.04 LTS jammy	Fixed 0.22-1ubuntu0.1
	20.04 LTS focal	Fixed 0.21-2ubuntu0.1+esm1
	18.04 LTS bionic	Fixed 0.21-1ubuntu0.18.04.1~esm1
	16.04 LTS xenial	Ignored end of ESM support, was needs-triage

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Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-8406-1
Net::CIDR::Lite vulnerabilities
8 June 2026