CVE-2021-4477

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.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

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

Configurations

No configuration.

History

03 Apr 2026, 23:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-03 23:17

Updated : 2026-06-17 04:19

NVD link : CVE-2021-4477

Mitre link : CVE-2021-4477

CVE.ORG link : CVE-2021-4477

JSON object : View

Products Affected

No product.

CWE

CWE-284

Improper Access Control

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