CVE-2026-40199: CWE-130 Improper Handling of Length Parameter Inconsistency in STIGTSP Net::CIDR::Lite
Net::CIDR::Lite versions before 0. 23 for Perl improperly handle IPv4 mapped IPv6 addresses, causing length inconsistencies in packed address representations. This leads to misaligned IPv4 parts and incorrect mask operations and address lookups, potentially allowing IP ACL bypass. The issue arises because the packing function includes an extra sentinel byte, producing an 18-byte value instead of the expected 17 bytes. This vulnerability affects valid RFC 4291 IPv4 mapped addresses and can cause the find() method to incorrectly match or miss addresses.
AI Analysis
Technical Summary
CVE-2026-40199 describes a vulnerability in Net::CIDR::Lite (Perl module) versions before 0.23 where the _pack_ipv6() function incorrectly includes a sentinel byte from _pack_ipv4() when packing IPv4 mapped IPv6 addresses (::ffff:x.x.x.x). This results in an 18-byte packed address instead of 17 bytes, misaligning the IPv4 portion. Consequently, bitwise mask operations and string comparisons used in find() and bin_find() methods produce incorrect results, potentially allowing IP ACL bypass by matching or missing addresses incorrectly. The vulnerability specifically affects valid IPv4 mapped IPv6 addresses as defined in RFC 4291.
Potential Impact
The vulnerability can cause IP access control lists (ACLs) relying on Net::CIDR::Lite to incorrectly allow or deny traffic due to improper address matching. This misalignment in address length and incorrect mask operations may lead to bypass of intended IP restrictions. No known exploits in the wild have been reported. The impact is limited to systems using vulnerable versions of Net::CIDR::Lite for IP address filtering involving IPv4 mapped IPv6 addresses.
Mitigation Recommendations
Patch status is not yet confirmed — no official fix or patch is currently available for this vulnerability. Users should monitor the vendor or CPAN security advisories for updates. Until a fix is released, avoid relying on Net::CIDR::Lite versions before 0.23 for IP filtering involving IPv4 mapped IPv6 addresses or implement additional validation to compensate for this issue.
CVE-2026-40199: CWE-130 Improper Handling of Length Parameter Inconsistency in STIGTSP Net::CIDR::Lite
Description
Net::CIDR::Lite versions before 0. 23 for Perl improperly handle IPv4 mapped IPv6 addresses, causing length inconsistencies in packed address representations. This leads to misaligned IPv4 parts and incorrect mask operations and address lookups, potentially allowing IP ACL bypass. The issue arises because the packing function includes an extra sentinel byte, producing an 18-byte value instead of the expected 17 bytes. This vulnerability affects valid RFC 4291 IPv4 mapped addresses and can cause the find() method to incorrectly match or miss addresses.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40199 describes a vulnerability in Net::CIDR::Lite (Perl module) versions before 0.23 where the _pack_ipv6() function incorrectly includes a sentinel byte from _pack_ipv4() when packing IPv4 mapped IPv6 addresses (::ffff:x.x.x.x). This results in an 18-byte packed address instead of 17 bytes, misaligning the IPv4 portion. Consequently, bitwise mask operations and string comparisons used in find() and bin_find() methods produce incorrect results, potentially allowing IP ACL bypass by matching or missing addresses incorrectly. The vulnerability specifically affects valid IPv4 mapped IPv6 addresses as defined in RFC 4291.
Potential Impact
The vulnerability can cause IP access control lists (ACLs) relying on Net::CIDR::Lite to incorrectly allow or deny traffic due to improper address matching. This misalignment in address length and incorrect mask operations may lead to bypass of intended IP restrictions. No known exploits in the wild have been reported. The impact is limited to systems using vulnerable versions of Net::CIDR::Lite for IP address filtering involving IPv4 mapped IPv6 addresses.
Mitigation Recommendations
Patch status is not yet confirmed — no official fix or patch is currently available for this vulnerability. Users should monitor the vendor or CPAN security advisories for updates. Until a fix is released, avoid relying on Net::CIDR::Lite versions before 0.23 for IP filtering involving IPv4 mapped IPv6 addresses or implement additional validation to compensate for this issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- CPANSec
- Date Reserved
- 2026-04-09T22:12:06.334Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d9743b1cc7ad14daee2672
Added to database: 4/10/2026, 10:05:47 PM
Last enriched: 4/10/2026, 10:20:46 PM
Last updated: 4/11/2026, 12:29:38 AM
Views: 6
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