PatchSiren cyber security CVE debrief

CVE-2026-45191 STIGTSP CVE debrief

CVE-2026-45191 is a vulnerability in Net::CIDR::Lite versions before 0.24 for Perl. The issue arises from the library's failure to properly consider extraneous zero characters in CIDR mask values, which may allow IP ACL bypass. For instance, mask forms like '/00' and '/01' pass validation and parse to the same prefix as their unpadded value. This vulnerability has a CVSS score of 6.5 and a severity of MEDIUM. Users of affected versions should prioritize updating to version 0.24 or later.

Vendor: STIGTSP
Product: Net::CIDR::Lite
CVSS: MEDIUM 6.5
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-10
Original CVE updated: 2026-07-24
Advisory published: 2026-05-10
Advisory updated: 2026-07-24

Who should care

Users of Net::CIDR::Lite versions before 0.24 for Perl should be aware of this vulnerability as it may allow IP ACL bypass. This includes operators, platform administrators, vulnerability management teams, and security teams who need to assess and mitigate this vulnerability in their environments.

Technical summary

The vulnerability is caused by the library's improper handling of CIDR mask values with extraneous zero characters. This could lead to IP ACL bypass as certain mask forms are parsed to the same prefix as their unpadded value. The affected product is Net::CIDR::Lite versions before 0.24 for Perl. There are no known exploits, but defenders should be aware of the potential impact and plan for updates or mitigations.

Defensive priority

Medium priority should be given to updating Net::CIDR::Lite to version 0.24 or later to mitigate this vulnerability.

Recommended defensive actions

Update Net::CIDR::Lite to version 0.24 or later
Review and update IP ACL configurations
Monitor for potential IP ACL bypass attempts
Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
Review compensating controls for exposed systems while remediation is scheduled and verified
Check relevant monitoring, detection, and logs for exposed assets that need extra review
Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-05-10T21:16:29.380Z and was last modified on 2026-07-24T13:10:00.223Z. The NVD entry is currently Deferred. Evidence is limited to public sources and may not reflect the full scope or impact of this vulnerability. Defenders should verify affected deployments and review official advisories for specific guidance.

Sources and references

Verified primary and authoritative sources

CVE-2026-45191 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-45191

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-45191 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45191

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Source reference
Unverified legacy reference

URL: https://github.com/stigtsp/Net-CIDR-Lite/commit/24e2c439ec405e5256024b9acefd4f7008c5ed0c.patch

9b29abf9-4ab0-4765-b253-1875cd9b441e
Source reference
Unverified legacy reference

URL: https://metacpan.org/release/STIGTSP/Net-CIDR-Lite-0.24/changes

9b29abf9-4ab0-4765-b253-1875cd9b441e
Source reference
Unverified legacy reference

URL: https://www.cve.org/CVERecord?id=CVE-2026-45190

9b29abf9-4ab0-4765-b253-1875cd9b441e

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.