CVE-2020-3139Network attack vector

Unauthorized port access via misprogrammed deny rules

Published Jan 26, 2020 · Updated Nov 15, 2024

Improper input validation in Cisco APIC before 4.2(3j) allows remote attackers to bypass OOB management IP-port deny rules. The OOB iptables programming logic records a denied port in configuration but fails to program the corresponding packet-drop rule. Unauthenticated traffic can reach a port that policy shows as denied, without granting control over device configuration.

CVSS severity5.3
Medium
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Cisco APIC before 4.2(3j) allows remote attackers to bypass OOB management IP-port deny rules. The OOB iptables programming logic records a denied port in configuration but fails to program the corresponding packet-drop rule. Unauthenticated traffic can reach a port that policy shows as denied, without granting control over device configuration.

The record

CVE
CVE-2020-3139
Published
Jan 26, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco Application Policy Infrastructure Controller (APIC)
Classifications
CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 26, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 2024Record 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=prior to 4.2(3j)

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Application Policy Infrastructure Controller (APIC)version=prior to 4.2(3j)

Published CVSS scores

5.3CiscoCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:X/RL:X/RC:X

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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