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.
Published: 2026-04-03
Score: 9.3 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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History

Fri, 03 Apr 2026 22:45:00 +0000

Type Values Removed Values Added
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.
Title Hirschmann HiLCOS OpenBAT BAT450 IPv6 IPsec Firewall Bypass
Weaknesses CWE-284
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-04-03T22:37:45.879Z

Reserved: 2026-04-03T16:46:37.018Z

Link: CVE-2021-4477

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-03T23:17:01.043

Modified: 2026-04-03T23:17:01.043

Link: CVE-2021-4477

cve-icon Redhat

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cve-icon OpenCVE Enrichment

No data.

Weaknesses