CRITICALVulnerability
Verified
Global

NVD CRITICAL: CVE-2021-4477 — Hirschmann HiLCOS OpenBAT and BAT450 products contain a firewall bypass vulnerab...

Friday, April 3, 2026 at 11:17 PM UTC·Source: NIST NVD

Updated: Monday, April 6, 2026 at 12:17 AM UTC

Executive Summary

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.

Analysis

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. CVSS Score: 9.1. Published: 2026-04-03T23:17:01.043.

Indicators of Compromise (1)

CVE (1)
CVE-2021-4477
NVDMITRE CVE
Source Attribution

Originally published by NIST NVD on Apr 3, 2026. Verified by: NIST.

Related Threats

MEDIUMVulnerability

The End of Static Security: Why AI Demands Real-Time Microsegmentation

AI is compressing cyberattack timelines from months to minutes. While segmentation has been a gold standard security practice for years, many organizations are still operating with outdated, static approaches.

Bank Info Security
MEDIUMVulnerability

Why Data Security Standards in Cancer Innovation Matter

Cancer research and treatment innovation - and the tech that powers that - requires a great deal of collaboration and data sharing among multiple parties. But keeping that sensitive information secure and private is crucial - and requires adherence to standards, said Baxter Lee of Clearwater.

Bank Info Security
MEDIUMVulnerability

One-Time Passcodes Are Gateway for Financial Fraud Attacks

<img src="https://ismg-cdn.nyc3.cdn.digitaloceanspaces.com/articles/one-time-passcodes-are-gateway-for-financial-fraud-attacks-image_small-6-a-31341.jpg" align=right hspace=4><b>Report Reveals Growing Trend of Fraudsters Intercepting SMS-Based Verification</b><br>Financial institutions have historically relied on one-time passcodes as a primary authentication control for their accountholders. But

Bank Info Security