CVE-2021-4477: Hirschmann HiLCOS OpenBAT BAT450 IPv6 IPsec Firewall Bypass
Belden · Hirschmann HiLCOS OpenBAT
Vendor fix available · Affected: Belden Hirschmann HiLCOS OpenBAT · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 26% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Belden · Hirschmann HiLCOS OpenBAT3.80-REL; 8.90-REL; 9.00-REL; 9.00-RU1; 9.10-REL; 9.12-REL and 13 more
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- Belden
- Published
- April 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2021-4477 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.