Security readout for executives and security teams
Plain-English summary
This flaw affects Moxa NPort IAW5000A-I/O serial device servers. A remote attacker could crash the device or run code through the built-in web server if vulnerable firmware is reachable. For industrial environments, this can threaten availability and device integrity.
Executive priority
Treat this as a high-priority OT exposure issue. Prioritize internet-reachable or broadly accessible devices first, because the vulnerability is unauthenticated, network reachable, and can affect both availability and control of affected systems.
Technical view
CVE-2021-32976 covers five stack-based buffer overflows in the built-in web server of Moxa NPort IAW5000A-I/O firmware version 2.2 or earlier. The CVSS 3.1 score is 9.8, with network access, low complexity, no privileges, and no user interaction required.
Likely exposure
Exposure is likely where Moxa NPort IAW5000A-I/O devices run firmware 2.2 or earlier and their web management service is reachable from operational networks, enterprise networks, or the internet.
Exploitation context
The provided sources support remote denial of service and arbitrary code execution potential. The bundle does not show CISA KEV listing or other evidence of active exploitation, so active exploitation should not be assumed.
Researcher notes
The source bundle identifies CWE-121 and five web-server buffer overflows but does not provide vulnerable endpoints, payload details, or exact fixed firmware. Validation should stay focused on asset, version, and reachability checks, then map remediation to vendor guidance.
Mitigation direction
- Identify deployed NPort IAW5000A-I/O devices and firmware versions.
- Review Moxa’s advisory for fixed firmware or supported remediation.
- Restrict access to the built-in web server to trusted management networks.
- Remove internet exposure and unnecessary routing to OT management interfaces.
- Monitor affected devices for crashes, resets, or unexpected configuration changes.
Validation and detection
- Inventory assets for Moxa NPort IAW5000A-I/O series devices.
- Confirm firmware is version 2.2 or earlier before marking vulnerable.
- Check network paths to the device web server from untrusted segments.
- Verify remediation status against Moxa and CISA advisory guidance.
- Review logs and monitoring for availability or integrity anomalies.
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.
CWE-121: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-32976 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.cisa.gov/uscert/ics/advisories/icsa-21-187-01CVE reference · x_refsource_CONFIRM
- https://www.moxa.com/en/support/product-support/security-advisory/nport-iaw5000a-io-serial-device-server-vulnerabilitiesCVE reference · x_refsource_CONFIRM
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.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.