Security readout for executives and security teams
Plain-English summary
This vulnerability can let someone with Modbus access disrupt affected Schneider Electric Modicon controllers by writing out-of-bounds variables. The described impact is denial of service, which can affect industrial availability. Business urgency depends on whether these controllers are reachable from untrusted networks or poorly segmented OT environments.
Executive priority
Treat this as a high-priority OT availability issue when affected controllers are reachable beyond tightly controlled engineering networks. It is less urgent for isolated systems with strict Modbus filtering, but still warrants inventory and vendor-advisory review.
Technical view
CVE-2018-7857 is described as a CWE-248 uncaught exception in all versions of Modicon M580, M340, Quantum, and Premium controllers. The trigger is writing out-of-bounds variables to the controller over Modbus, causing possible denial of service. The provided bundle does not include CVSS scoring.
Likely exposure
Exposure is most likely where affected Modicon PLCs accept Modbus traffic from engineering workstations, plant networks, remote access paths, or any less-trusted segment. Internet exposure is not stated in the sources and should not be assumed.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. Public references from Schneider Electric and Cisco Talos exist, but the provided data only supports a Modbus-access denial-of-service risk, not confirmed real-world exploitation.
Researcher notes
Evidence is limited to the CVE description and listed Schneider Electric and Talos references. Avoid assuming code execution, data theft, internet-wide exploitation, or a specific patch version unless confirmed in vendor guidance.
Mitigation direction
- Review Schneider Electric advisory SEVD-2019-134-11 for vendor-approved remediation.
- Restrict Modbus access to trusted engineering and control hosts only.
- Segment affected PLCs from corporate, guest, and internet-facing networks.
- Monitor OT networks for unexpected Modbus write activity.
- Prioritize remediation where controllers support safety-critical or production processes.
Validation and detection
- Inventory Modicon M580, M340, Quantum, and Premium controllers.
- Confirm which controllers accept Modbus traffic and from where.
- Check firmware and advisory status against Schneider Electric guidance.
- Review firewall rules and remote access paths to PLC networks.
- Assess monitoring coverage for Modbus writes and controller faults.
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-2018-7857 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.schneider-electric.com/en/download/document/SEVD-2019-134-11/CVE reference · x_refsource_MISC
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2019-0768CVE 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.