CVE-2026-40199Disclosure(stigtsp / net\)

LOWCVSS 6.5 · MEDIUM

Signal is active with 4 mentions in latest observed window

Immediate actions

Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD 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.

stigtsp CVEs Back to dashboard

0.0/ 10 priority

Sources & remediation

Patch / fix

https://github.com/stigtsp/Net-CIDR-Lite/commit/b7166b1fa17b3b14b4c795ace5b3fbf71a0bd04a.patch

Vendor / third-party advisories

https://www.cve.org/CVERecord?id=CVE-2026-40198

Other references

https://metacpan.org/release/STIGTSP/Net-CIDR-Lite-0.23/changes

Weakness type (CWE)

CWE-130

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

AVAILABLE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

net\

Threat summary

4 mentions across 1 observed day

What's happening

Technical details provided in 4 signals
Disclosure: 3 classified signals
General: 1 classified signal
4 total mentions across 1 day

Affected systems

Vendors

stigtsp

Products

net\

1 version affected across 1 product

Deep dive

Activity timeline4 mentions / 1d

Signal classification2 categories

Disclosure

375.0%

General

125.0%

Referenced assets6 URLs

By indicator

Full discourse4 posts

Open Source Security mailing list@oss_security180d
Disclosure
Perl CPAN CVE-2026-40198: Net::CIDR::Lite before 0.23 does not validate IPv6 group count, which may allow IP ACL bypass https://www.openwall.com/lists/oss-security/2026/04/11/1 CVE-2026-40199: Net::CIDR::Lite before 0.23 mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass https://www.openwall.com/lists/oss-security/2026/04/11/2
Post summary
The post discloses two Net::CIDR::Lite CVEs that enable IP ACL bypass due to insufficient validation; no PoC, exploit, or patch information is present.
00030374
4.6K followersView on X
CVE@CVEnew180d
Disclosure
CVE-2026-40199 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 _pac… https://www.cve.org/CVERecord?id=CVE-2026-40199
Post summary
The post announces that Net::CIDR::Lite versions before 0.23 have a flaw where IPv4‑mapped IPv6 addresses are mishandled, potentially enabling bypass of IP access control lists.
00010184
57.7K followersView on X
CyberDudeBivash® | Global Cybersecurity Company@cyberbivash180d
Disclosure
🚨 CYBERDUDEBIVASH SENTINEL APEX ALERT 🚨 Threat: CVE-2026-40199: Net::CIDR::Lite versions before 0.23 for Perl mishandles IPv4 mapped IPv6 addresses, which may allow IP ACL bypass Intel Report: https://ift.tt/nTXpwL0
Post summary
The post announces CVE-2026-40199 affecting Net::CIDR::Lite, noting a flaw that could allow IP ACL bypass via IPv4‑mapped IPv6 addresses; no exploit, patch, or active use is reported.
0000030
280 followersView on X
Vulmon Vulnerability Feed@VulmonFeeds180d
General
CVE-2026-40199 IP ACL Bypass via IPv4 Mapped IPv6 Address Mishandling in Net::CIDR::Lit... https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-40199 Vulnerability Notification: https://alerts.vulmon.com/?utm_source=twitter&utm_medium=social&utm_campaign=2102281&utm_content=3
Post summary
The message notes CVE-2026-40199 and provides a concise technical description of an IP ACL bypass involving IPv4 mapped IPv6 addresses, but offers no further details such as PoC, exploit code, or remediation.
0000077
4.0K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	stigtsp	net\	\	-	-

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What researchers are saying

CVE-2026-40199

Open Source Security mailing list@oss_securityDisclosure

The post discloses two Net::CIDR::Lite CVEs that enable IP ACL bypass due to insufficient validation; no PoC, exploit, or patch information is present.

CVE@CVEnewDisclosure

The post announces that Net::CIDR::Lite versions before 0.23 have a flaw where IPv4‑mapped IPv6 addresses are mishandled, potentially enabling bypass of IP access control lists.

CyberDudeBivash® | Global Cybersecurity Company@cyberbivashDisclosure

The post announces CVE-2026-40199 affecting Net::CIDR::Lite, noting a flaw that could allow IP ACL bypass via IPv4‑mapped IPv6 addresses; no exploit, patch, or active use is reported.

Vulmon Vulnerability Feed@VulmonFeedsGeneral

The message notes CVE-2026-40199 and provides a concise technical description of an IP ACL bypass involving IPv4 mapped IPv6 addresses, but offers no further details such as PoC, exploit code, or remediation.