VulnerabilityPublished 10 May 2026

CVE-2026-45191: STIGTSP Net::CIDR::Lite · Improper Validation of Unsafe Equivalence in Input

Affects STIGTSP Net::CIDR::LiteSource CVE Database V5

Compare

Not known to be exploited · CVSS 6.5 Medium : upgrade to 0.24 when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.24

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Net::CIDR::Lite and Net-CIDR-Lite to 0.24.

Affected software

Product	Affected	Fixed in
STIGTSPNet::CIDR::Lite	Affected <0.24	Fixed in 0.24
GitHubNet-CIDR-Lite`pkg:github/Net-CIDR-Lite`Other threats	Affected <0.24	Fixed in 0.24

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, users should consider implementing additional validation on CIDR mask inputs to reject extraneous zero characters or avoid relying solely on vulnerable versions of Net::CIDR::Lite for critical IP ACL enforcement.

Description

Net::CIDR::Lite versions before 0.24 for Perl improperly validate CIDR mask values by allowing extraneous zero characters such as "/00" and "/01". These mask forms pass validation and parse to the same prefix as their unpadded counterparts, potentially enabling IP ACL bypass. This vulnerability is identified as CWE-1289 and has a CVSS score of 6.5, indicating medium severity. There are no known exploits in the wild at this time.

Impact

An attacker could exploit this vulnerability to bypass IP-based access controls by using specially crafted CIDR mask values with extraneous zeros. This could allow unauthorized access or disruption of services protected by IP ACLs relying on Net::CIDR::Lite for mask validation. There is no evidence of confidentiality impact, but integrity and availability impacts are rated as low and low respectively. No known exploits have been reported in the wild.

Summary

The vulnerability in Net::CIDR::Lite (prior to version 0.24) arises from improper validation of CIDR mask inputs, specifically failing to reject extraneous zero characters in mask values. This allows mask forms like "/00" and "/01" to be accepted and parsed equivalently to their unpadded forms, which can lead to IP Access Control List (ACL) bypass. The issue is tracked as CVE-2026-45191 and classified under CWE-1289 (Improper Validation of Unsafe Equivalence in Input). The CVSS 3.1 base score is 6.5, reflecting a medium severity with network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality impact, limited integrity impact, and limited availability impact.

CWE-1289Improper Validation of Unsafe Equivalence in Input (opens in a new tab)
Base weakness
The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 May 2026, 10:44 UTC

WeaknessesCWE-1289

Technical details

References

Community reviews

Related threats