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CVE-2026-40199— Net::CIDR::Lite versions before 0.23 for Perl mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass

Quick assessment

Affected
STIGTSP Net::CIDR::Lite
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Net-CIDR-Lite是Stig个人开发者的一个用于处理CIDR地址的Perl模块。 Net-CIDR-Lite 0.23之前版本存在安全漏洞，该漏洞源于错误处理IPv4映射的IPv6地址，可能导致IP访问控制列表绕过。

AI Predicted 5.9 Difficulty: Moderate EPSS 0.31% · P23

Possible ATT&CK Techniques 1 AI

T1001 · Data Obfuscation
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I. Basic Information for CVE-2026-40199

Vulnerability Information
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Vulnerability Title
Net::CIDR::Lite versions before 0.23 for Perl mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
长度参数不一致性处理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Net-CIDR-Lite 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Net-CIDR-Lite是Stig个人开发者的一个用于处理CIDR地址的Perl模块。 Net-CIDR-Lite 0.23之前版本存在安全漏洞，该漏洞源于错误处理IPv4映射的IPv6地址，可能导致IP访问控制列表绕过。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
STIGTSP Net::CIDR::Lite 0 ~ 0.23 -

II. Public POCs for CVE-2026-40199

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III. Intelligence Information for CVE-2026-40199

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Patches & Fixes for CVE-2026-40199 (1)

Vendor Advisories for CVE-2026-40199 (1)

Other References for CVE-2026-40199 (1)

IV. Related Vulnerabilities

Same product: Net::CIDR::Lite
Same vendor: STIGTSP
Same weakness: CWE-130