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CVE Record

CVE-2020-4320: IBM MQ Appliance and IBM MQ AMQP Channels 8.0, 9.0 LTS, 9.1 LTS, and 9.1 CD do not correctly block or allow...

IBM MQ Appliance and IBM MQ AMQP Channels 8.0, 9.0 LTS, 9.1 LTS, and 9.1 CD do not correctly block or allow clients based on the certificate distinguished name SSLPEER setting. IBM X-Force ID: 177403.

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2020-4320 affects IBM MQ Appliance and IBM MQ AMQP Channels. The product may mishandle certificate distinguished name rules used to allow or block clients, creating an availability risk. The published CVSS score is medium, but business impact depends on whether affected MQ services support important messaging workflows.

Executive priority

Treat as a scheduled remediation item unless the affected MQ environment supports critical operations or is broadly reachable. Prioritize faster action for production messaging systems that rely on certificate-based client filtering.

Technical view

IBM reports that MQ 8.0, 9.0 LTS, 9.1 LTS, and 9.1 CD do not correctly enforce SSLPEER certificate distinguished name allow/block decisions. The CVSS vector is network-reachable with low privileges, high attack complexity, and high availability impact, with no confidentiality or integrity impact stated.

Likely exposure

Exposure is most likely where affected IBM MQ Appliance or MQ AMQP Channels are deployed and AMQP client access depends on SSLPEER certificate distinguished name filtering. Internet exposure is not stated in the sources.

Exploitation context

The provided sources do not show CISA KEV listing or confirmed active exploitation. IBM X-Force tracks the issue as 177403. The CVSS vector indicates exploitation requires low privileges and high attack complexity.

Researcher notes

Evidence is limited to CVE, IBM advisory, and X-Force metadata. No CWE is listed. The issue is an authorization decision flaw around SSLPEER matching with availability impact. Public sources supplied here do not provide exploit details or specific fixed version numbers.

Mitigation direction

  • Identify affected IBM MQ Appliance and MQ AMQP Channel deployments.
  • Review IBM advisory 5736885 for fixed levels or vendor mitigations.
  • Apply IBM-provided updates or configuration guidance where applicable.
  • Limit network access to MQ AMQP endpoints to trusted clients.
  • Avoid relying on SSLPEER as the only access control until remediated.

Validation and detection

  • Inventory IBM MQ versions 8.0, 9.0 LTS, 9.1 LTS, and 9.1 CD.
  • Confirm whether AMQP Channels are enabled and using SSLPEER rules.
  • Review channel authentication and certificate distinguished name policies.
  • Check vendor advisory status against installed MQ maintenance levels.
  • Monitor MQ availability and unexpected client access events.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2020-4320 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.3 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/AV:N/I:N/AC:H/S:U/PR:L/A:H/C:N/UI:N/RC:C/RL:O/E:U

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.3CVSS 3.0MediumCVSS:3.0/AV:N/I:N/AC:H/S:U/PR:L/A:H/C:N/UI:N/RC:C/RL:O/E:U1.63.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

5.3Medium
CVSS 3.0 vector shape for CVE-2020-4320Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/AV:N/I:N/AC:H/S:U/PR:L/A:H/C:N/UI:N/RC:C/RL:O/E:U

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
IBMMQ8.0, 9.0.LTS, 9.1.LTS, 9.1.CDListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.