Status: UPDATED
| Advisory ID: CVE-2021-4477
Key Details
| CVE | CVE-2021-4477 |
| CVSS Score / Version | 9.1 (Critical) / CVSS v3.1 |
| Updated | 2026-07-24 |
| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| CVSS Prose | attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is none. |
| Affected products | Belden Hirschmann HiLCOS OpenBAT |
| Classified as | CWE-284 (Improper Access Control) |
Affected Products, Subsystems & Sectors
| Subsystems | General OT |
| Sectors | Multiple |
What to Know
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. (NVD)
What to Do
Monitor Belden's web page for any future patch releases.
References