CVE-2026-40199 Affecting perl-Net-CIDR-Lite package, versions <0:0.22-8.amzn2023.0.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-AMZN2023-PERLNETCIDRLITE-16352403
- published3 May 2026
- disclosed10 Apr 2026
Introduced: 10 Apr 2026
CVE-2026-40199 (opens in a new tab)How to fix?
Upgrade Amazon-Linux:2023 perl-Net-CIDR-Lite to version 0:0.22-8.amzn2023.0.1 or higher.
This issue was patched in ALAS2023-2026-1624.
NVD Description
Note: Versions mentioned in the description apply only to the upstream perl-Net-CIDR-Lite package and not the perl-Net-CIDR-Lite package as distributed by Amazon-Linux.
See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.
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.