Security readout for executives and security teams
Plain-English summary
CVE-2021-27478 can let an unauthenticated network attacker crash or disrupt systems using older EIPStackGroup OpENer EtherNet/IP code. The business concern is operational downtime in environments where this industrial communication stack is exposed or embedded. The provided sources do not identify specific downstream devices or active exploitation.
Executive priority
Prioritize remediation for any production OT or industrial environment where OpENer is reachable across a network. The risk is mainly outage, not data theft, but availability loss in control environments can create operational impact. Unknown downstream exposure lowers confidence, not urgency for confirmed deployments.
Technical view
The issue is CWE-681, incorrect conversion between numeric types, in OpENer EtherNet/IP commits and versions before February 10, 2021. A crafted packet may cause denial of service. CVSS 3.1 is 8.2: network reachable, low complexity, no privileges, no user interaction, low integrity impact, and high availability impact.
Likely exposure
Exposure is most likely in industrial or OT deployments, test systems, or embedded products using OpENer EtherNet/IP code from before February 10, 2021. The bundle lists no CPEs, no named downstream vendors, and unspecified affected versions beyond the date boundary.
Exploitation context
The CVE describes network-based unauthenticated denial of service from a crafted packet. CISA KEV status is false in the bundle, and no cited source here confirms active exploitation. Treat internet-facing or flat OT network exposure as higher urgency.
Researcher notes
Evidence supports a network-triggered denial-of-service condition in pre-February 10, 2021 OpENer code. The source bundle does not provide exploit details, affected CPEs, downstream products, or confirmed exploitation. Validate by version and code provenance rather than product name alone.
Mitigation direction
- Inventory systems or products using EIPStackGroup OpENer EtherNet/IP.
- Upgrade OpENer code to a version or commit from February 10, 2021 or later.
- Check CISA and the EIPStackGroup repository for vendor-specific guidance.
- Restrict network access to EtherNet/IP services to trusted management and OT segments.
- Monitor affected segments for unexpected service restarts or communication failures.
Validation and detection
- Confirm whether OpENer EtherNet/IP is present in source, firmware, or product SBOMs.
- Verify the deployed OpENer commit or release date is February 10, 2021 or later.
- Review network paths to ensure untrusted hosts cannot reach affected services.
- Check logs and uptime data for unexplained denial-of-service symptoms.
- Document any downstream products where version evidence is unavailable.
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-681: 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 lookupCVE-2021-27478 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
- High
- CVSS
- 8.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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:N/I:L/A:H3.94.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.2HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.cisa.gov/uscert/ics/advisories/icsa-21-105-02CVE reference · x_refsource_CONFIRM
- https://github.com/EIPStackGroup/OpENerCVE 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.
Incorrect Conversion between Numeric Types
Incorrect Conversion between Numeric Types represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.