Is CVE-2026-40198 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-40198 being exploited in the wild.

How severe is CVE-2026-40198?

High severity, with a CVSS score of 7.5, published 10 April 2026.

Which products and versions are affected?

Stig Palmquist (STIGTSP) Net::CIDR::Lite versions before 0.23.

Is there a fix for CVE-2026-40198?

A patch was published on 2026-04-10: Fixed in version 0.23 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-40198 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-40198?

Check whether you run Stigtsp Net\. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-40198: Net::CIDR::Lite IP ACL bypass via improper IPv6 validation

CVE-2026-40198 · Severity: high · CVSS 7.5 · Published 2026-04-10

A vulnerability in a popular Perl library used for managing IP address ranges could allow attackers to bypass security access controls. By providing malformed IPv6 addresses, an attacker can trick the software into incorrectly identifying an address as being part of a trusted network. This could lead to unauthorized access to restricted services or data that rely on IP-based filtering.

Quick answers

Is CVE-2026-40198 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-40198 being exploited in the wild.
How severe is CVE-2026-40198?: High severity, with a CVSS score of 7.5, published 10 April 2026.
Which products and versions are affected?: Stig Palmquist (STIGTSP) Net::CIDR::Lite versions before 0.23.
Is there a fix for CVE-2026-40198?: A patch was published on 2026-04-10: Fixed in version 0.23 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-40198 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-40198?: Check whether you run Stigtsp Net\. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability exists in the _pack_ipv6() function of Net::CIDR::Lite before version 0.23. The function fails to verify that uncompressed IPv6 addresses (those without the '::' shorthand) contain exactly eight hex groups. When malformed inputs with fewer groups are provided, the library generates packed binary values of incorrect lengths. Because internal functions like find() and bin_find() use standard Perl string comparisons (lt/gt) on these packed values, comparing strings of mismatched lengths results in incorrect logic, potentially returning 'true' for addresses that should be outside a specified CIDR range. This is fixed in version 0.23 by ensuring the group count is strictly validated.

Affected products

Stig Palmquist (STIGTSP) Net::CIDR::Lite versions before 0.23

Timeline

2026-04-10: disclosed
2026-04-10: patched: Fixed in version 0.23
2026-04-10: advisory

References

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