Critical severity9.1NVD Advisory· Published Apr 3, 2026· Updated Apr 7, 2026
CVE-2021-4477
CVE-2021-4477
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.
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Affected products
1Patches
Vulnerability mechanics
References
2News mentions
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