VULNERABILITY INTELLIGENCE
CVE-2021-4477
CVSS score9.1 CRITICAL
EPSS probability0.33%
CISA KEVNot currently listed
Published2026-04-03
Last modified2026-07-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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.
Weakness classification
- disclosure@vulncheck.com: CWE-284