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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.

PUBLISHED Reserved 2026-04-03 | Published 2026-04-03 | Updated 2026-04-06 | Assigner VulnCheck




CRITICAL: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CRITICAL: 9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Problem types

CWE-284 Improper access control

Product status

Default status
unaffected

3.80-REL (custom)
affected

8.90-REL (custom)
affected

9.00-REL (custom)
affected

9.00-RU1 (custom)
affected

9.10-REL (custom)
affected

9.12-REL (custom)
affected

9.12-RU1 (custom)
affected

9.12-RU2 (custom)
affected

9.12-RU3 (custom)
affected

9.12-RU4 (custom)
affected

9.12-RU5 (custom)
affected

9.12-RU6 (custom)
affected

9.12-RU7 (custom)
affected

9.12-RU8 (custom)
affected

9.12-RU9 (custom)
affected

9.13-REL (custom)
affected

9.13-RU1 (custom)
affected

10.12-REL (custom)
affected

10.12-RU1 (custom)
affected

10.12-RU2 (custom)
unaffected

References

assets.belden.com/...Security-Bulletin-BSECV-1v0-2019-09.pdf vendor-advisory

www.vulncheck.com/...enbat-bat450-ipv6-ipsec-firewall-bypass

cve.org (CVE-2021-4477)

nvd.nist.gov (CVE-2021-4477)

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