Security readout for executives and security teams
Plain-English summary
CVE-2021-43556 affects FATEK WinProladder project-file handling. A crafted project file could crash or take over the application when opened, potentially giving an attacker code execution on an engineering workstation.
Executive priority
Treat this as a high-priority OT workstation risk, not an internet-facing emergency. Prioritize sites using FATEK PLC engineering workflows and reduce unsafe project-file handling until vendor guidance is applied.
Technical view
The vulnerability is a stack-based buffer overflow, CWE-121, in FATEK WinProladder 3.30_24518 and prior while processing project files. CVSS 3.1 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 OT engineering or maintenance workstations where FATEK WinProladder is installed and users open project files from email, shared drives, vendors, or removable media.
Exploitation context
The source bundle does not report active exploitation, and KEV status is false. Practical exploitation requires convincing a user to open a malicious project file locally, so phishing, vendor file exchange, or compromised shared repositories are the main concern.
Researcher notes
Evidence supports arbitrary code execution through crafted project-file parsing. The CVSS vector confirms local execution with required user interaction and no privileges. The bundle does not include exploit maturity, proof-of-concept status, or a named fixed version.
Mitigation direction
- Identify WinProladder installations and versions, especially 3.30_24518 and prior.
- Check FATEK and CISA guidance for the current supported update or vendor workaround.
- Do not open unexpected WinProladder project files from untrusted sources.
- Restrict engineering workstation access and file transfer paths.
- Use endpoint controls and backups appropriate for OT engineering systems.
Validation and detection
- Inventory OT workstations for FATEK WinProladder and record installed versions.
- Review whether project files arrive through email, shared folders, or removable media.
- Confirm users have guidance for handling unexpected project files.
- Check security tools for detections involving suspicious WinProladder process behavior.
- Document any affected systems and remediation owner.
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-2021-43556 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-21-320-01CVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-22-029/CVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-22-032/CVE reference · x_refsource_MISC
- https://www.zerodayinitiative.com/advisories/ZDI-22-031/CVE 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.
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.