CVE-2017-20233

Firewall bypass via unfiltered multicast and broadcast

Published Apr 3, 2026 · Updated Apr 3, 2026

Firewall filtering in Belden HiLCOS OpenBAT, BAT450, WLC, and BAT867 allows remote attackers to bypass IPv4 filter rules. The Layer-2 firewall omits configured filtering for IPv4 multicast and broadcast packets when management IP address filtering is disabled. Network adjacency and that disabled setting are required; attackers can inject or observe packets that the configured rules should block.

CVSS severity5.3
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firewall filtering in Belden HiLCOS OpenBAT, BAT450, WLC, and BAT867 allows remote attackers to bypass IPv4 filter rules. The Layer-2 firewall omits configured filtering for IPv4 multicast and broadcast packets when management IP address filtering is disabled. Network adjacency and that disabled setting are required; attackers can inject or observe packets that the configured rules should block.

The record

CVE
CVE-2017-20233
Published
Apr 3, 2026
Updated
Apr 3, 2026
Vendor
Belden Inc.
Product
Hirschmann HiLCOS
Classifications
CWE-284
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0
  2. Affected versionversion=0 <=9.10.5126-REL
  3. Affected versionversion=0 <=9.12.5500-REL
  4. Affected versionversion=0 <=9.14.5500-REL

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Belden Inc. · Hirschmann HiLCOSversion=0; version=0 <=9.10.5126-REL; version=0 <=9.12.5500-REL; version=0 <=9.14.5500-REL

Published CVSS scores

5.4VulnCheckCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
5.3VulnCheckCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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