🛡️ CVE-2026-40198 — net\

🟠 CVSS 7.5 — High ✅ No Known Exploit CWE-1286 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.

Affected software

CVE-2026-40198 is recorded against 1 package.

  • net\ (fixed in 0.23)

Timeline and source

Published on 10 April 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
metacpan.org
www.cve.org

CVE-2026-40198 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE CWE-1286
Public Exploit ✅ No
Source NVD
Published 2026-04-10
Updated 2026-08-11
Modified 2026-06-17

Affected Packages

Software From version Fixed in
net\ — 0.23

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