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.
Score
A numerical rating that indicates how dangerous this vulnerability is.
9.1Critical- Published Date:Apr 3, 2026
- CISA KEV Date:*No Data*
- Industries Affected:20
Exploitability
- Score:3.9
- Attack Vector:NETWORK
- Attack Complexity:LOW
- Privileges Required:NONE
- User Interaction:NONE
- Scope:UNCHANGED
Impact
- Score:5.2
- Confidentiality Impact:HIGH
- Integrity Impact:HIGH
- Availability Impact:NONE
Description Preview
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.
Industries Affected
Below is a list of industries most commonly impacted or potentially at risk based on intelligence.
