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CRITICAL

CVE-2021-4477

CVE-2021-4477 — Hirschmann HiLCOS OpenBAT BAT450 IPv6 IPsec Firewall Bypass

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 Updated Sources: cvelistV5, VulnCheck

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

belden

hirschmann_hilcos_openbat

CVSS base

9.1

CRITICAL

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

belden

Products (1)

hirschmann hilcos openbat

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
9.1CVSS 3.1CRITICAL——cvelistV5

Weakness & attack patterns

  • CWE-284

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1027.009Obfuscated Files or Information: Embedded Payloads
  • T1546.004Event Triggered Execution: .bash_profile and .bashrc
  • T1546.016Event Triggered Execution: Installer Packages

References

2 on the record

Elsewhere on this site

  • beldenevery CVE for this vendor
  • CWE-284other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.