Security readout for executives and security teams
Plain-English summary
This flaw affects listed WAGO industrial controllers. A logged-in attacker who can reach the device over the network may access files outside the intended home directory and gain higher-privilege filesystem access. In operational technology environments, that can expose sensitive configuration and affect integrity or availability, so exposed or broadly reachable controllers deserve urgent review.
Executive priority
Treat this as high-priority OT risk management, especially for controllers supporting production or safety-adjacent processes. The vulnerability is critical by CVSS, but known active exploitation is not supported by the provided sources.
Technical view
CVE-2021-21001 is a CWE-22 path traversal issue in WAGO Series PFC200 and Series Ethernet Controller firmware. The CVSS 3.1 vector is AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H, meaning network access and high privileges are required, but successful exploitation can heavily affect confidentiality, integrity, and availability.
Likely exposure
Exposure is most likely where affected WAGO controllers are reachable from corporate, vendor, remote-access, or internet-facing networks and where high-privilege credentials exist. The source bundle does not provide vulnerable firmware ranges or deployment prevalence.
Exploitation context
The bundle does not cite CISA KEV listing or public active exploitation. The attack requires an authorized high-privilege user with network access and specially crafted packets, so insider, compromised administrator, or poorly segmented remote access scenarios are the main concern.
Researcher notes
Evidence supports a path traversal-style file access issue with privilege impact on named WAGO controller models. The provided bundle lacks exact firmware ranges, patch versions, proof-of-concept status, and operational indicators; avoid broader claims without the VDE advisory details.
Mitigation direction
- Check the VDE/WAGO advisory for affected firmware and vendor-approved fixes or mitigations.
- Inventory listed WAGO PFC200 and Series Ethernet Controller models in OT environments.
- Restrict controller management access to trusted administration networks only.
- Review and reduce high-privilege accounts able to access affected devices.
- Prioritize remediation for controllers reachable from remote-access or corporate networks.
Validation and detection
- Match controller model numbers against the affected product lists in the CVE bundle.
- Confirm firmware status against the VDE/WAGO advisory before declaring systems remediated.
- Verify network paths to controllers from corporate, VPN, vendor, and internet-facing zones.
- Review administrator account inventory and recent access logs for unexpected activity.
- Document compensating controls where vendor remediation is not yet confirmed.
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-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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-2021-21001 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
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/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:H/UI:N/S:C/C:H/I:H/A:H2.36Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://cert.vde.com/en-us/advisories/vde-2021-014CVE 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.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.