Security readout for executives and security teams
Plain-English summary
CVE-2021-33823 is a denial-of-service issue reported for MOXA MGate MB3180 Version 2.1 Build 18113012. A large volume of TCP connection attempts can exhaust the device web service, making the web server unavailable. The sources do not provide CVSS scoring, vendor remediation details, or evidence of active exploitation.
Executive priority
Prioritize if these gateways support operational environments or if management interfaces are exposed. Business impact is service unavailability, not data theft based on current evidence. Urgency is lower where devices are isolated and vendor guidance is pending.
Technical view
The CVE describes TCP SYN packet volume exhausting web-service resources on MOXA MGate MB3180 Version 2.1 Build 18113012, causing denial of service. Available data is sparse: no CWE, CVSS, official fix, or expanded affected-version list is provided in the bundle.
Likely exposure
Exposure is most likely where MOXA MGate MB3180 devices on Version 2.1 Build 18113012 have their web service reachable from untrusted or weakly segmented networks. The source bundle does not prove other models or versions are affected.
Exploitation context
The bundle includes a public GitHub proof-of-concept reference, but CISA KEV is false and no cited source states active exploitation. Treat this as a publicly described DoS condition, not a confirmed campaign.
Researcher notes
The CVE record is narrow and incomplete: affected metadata is generic, severity is unknown, and remediation is not named. Do not extend impact beyond the MB3180 version/build in the description without vendor confirmation.
Mitigation direction
- Check MOXA guidance or support channels for firmware or configuration remediation.
- Limit access to the device web service to trusted management networks.
- Use segmentation or firewall rules to block untrusted TCP access.
- Apply network controls that reduce connection-flood impact where appropriate.
- Monitor device availability and web-service instability.
Validation and detection
- Inventory MOXA MGate MB3180 devices and record firmware/build versions.
- Identify whether Version 2.1 Build 18113012 is deployed.
- Confirm the web service is not reachable from untrusted networks.
- Review monitoring for unexplained web-service outages or resource exhaustion.
- Track vendor documentation for confirmed fixed versions or mitigations.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-33823 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.moxa.com/en/products/industrial-edge-connectivity/protocol-gateways/modbus-tcp-gateways/mgate-mb3180-mb3280-mb3480-seriesCVE reference · x_refsource_MISC
- https://github.com/Jian-Xian/CVE-POC/blob/master/CVE-2021-33823.mdCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.