Security readout for executives and security teams
Plain-English summary
WECON PLC Editor can mishandle crafted project files, potentially letting code run on the user’s machine when a file is opened. This is a high-impact issue for engineering environments because project files are part of normal PLC workflows.
Executive priority
Treat this as a targeted engineering-workstation risk rather than broad internet exposure. Prioritize sites using WECON PLC Editor, because compromise of an engineering workstation can affect operational technology workflows even when exploitation requires opening a malicious file.
Technical view
CVE-2021-42707 is a CWE-787 out-of-bounds write in WECON PLC Editor project-file processing. The CVSS 3.1 score is 7.8: local attack vector, low complexity, no privileges, user interaction required, with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on engineering workstations using WECON PLC Editor, especially where project files are received from vendors, contractors, email, USB media, or shared folders. The bundle identifies PLC Editor and names versions 1.3.8 and prior in the description.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. Exploitation requires user interaction because a crafted project file must be processed by PLC Editor. No remote network exploitation path is supported by the provided evidence.
Researcher notes
Evidence is limited to the CVE bundle and CISA advisory reference. The affected entry says all versions, while the description specifically says versions 1.3.8 and prior. No official patch details are present in the supplied bundle, so remediation should be verified with vendor guidance.
Mitigation direction
- Identify WECON PLC Editor installations and versions in engineering environments.
- Check WECON and CISA guidance for fixed versions or official mitigations.
- Restrict opening PLC project files from untrusted sources.
- Handle externally supplied project files in a controlled workstation workflow.
- Review email, USB, and file-share controls for engineering users.
Validation and detection
- Inventory workstations where WECON PLC Editor is installed.
- Confirm whether installed versions are 1.3.8 or prior.
- Review project-file intake paths from contractors, vendors, and removable media.
- Verify users have guidance not to open untrusted project files.
- Check whether compensating controls cover engineering file handling.
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-787: 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-2021-42707 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
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://us-cert.cisa.gov/ics/advisories/icsa-21-315-01CVE 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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.