Description

Hirschmann HiLCOS OpenBAT and BAT450 products contain a firewall bypass vulnerability in IPv6 IPsec deployments that allows traffic from VPN connections to bypass configured firewall rules. Attackers can exploit this vulnerability by establishing IPv6 IPsec connections (IKEv1 or IKEv2) while simultaneously using an IPv6 Internet connection to circumvent firewall policy enforcement.

INFO

Published Date :

2026-04-03T22:37:45.879Z

Last Modified :

2026-04-06T13:17:07.744Z

Source :

VulnCheck
AFFECTED PRODUCTS

The following products are affected by CVE-2021-4477 vulnerability.

Vendors Products
Belden
  • Hirschmann Hilcos Openbat
REFERENCES

Here, you will find a curated list of external links that provide in-depth information to CVE-2021-4477.

URL Resource
https://assets.belden.com/m/5fd1a50fa50cb252/original/Belden-Security-Bulletin-BSECV-1v0-2019-09.pdf cve-icon cve-icon
https://www.vulncheck.com/advisories/hirschmann-hilcos-openbat-bat450-ipv6-ipsec-firewall-bypass cve-icon cve-icon
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CVSS Vulnerability Scoring System

Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
VS Confidentiality
VS Integrity
VS Availability
SS Confidentiality
SS Integrity
SS Availability
Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact