Security readout for executives and security teams
Plain-English summary
CVE-2021-33535 affects specific Weidmüller industrial WLAN devices. An authenticated low-privilege user can use a crafted time server entry to trigger a format string flaw that may lead to remote code execution. For industrial networks, this can threaten device control, network availability, and operational trust boundaries.
Executive priority
Treat this as a high-priority industrial network exposure where affected devices are deployed. It requires authentication, but successful exploitation could allow code execution on WLAN infrastructure that supports operational connectivity.
Technical view
The issue is a CWE-134 format string vulnerability in iw_console conio_writestr. The CVSS 3.1 score is 8.8 with network attack vector, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely limited to environments using the listed Weidmüller IE-WL/IE-WLT BL or VL AP/CL industrial WLAN devices. Risk is higher where low-privilege users can authenticate to device management functions. The source bundle does not provide exact firmware ranges or internet-exposure evidence.
Exploitation context
The sources describe remote code execution after authenticated interaction with the time server configuration path. KEV status is false, and the provided sources do not state active exploitation in the wild or public exploit availability.
Researcher notes
Evidence supports a high-impact authenticated RCE risk, but the supplied bundle lacks patch version details, exploit telemetry, and full firmware applicability. Avoid assuming broader Weidmüller product impact without the vendor advisory or asset confirmation.
Mitigation direction
- Review Weidmüller/VDE advisory VDE-2021-026 for vendor-approved remediation guidance.
- Restrict device management access to trusted administrative networks only.
- Remove unnecessary low-privilege accounts and review account permissions.
- Monitor for unexpected time server configuration changes.
- Prioritize compensating controls if vendor remediation is not immediately available.
Validation and detection
- Inventory Weidmüller industrial WLAN devices and match listed product order numbers.
- Confirm whether any affected devices permit low-privilege authenticated configuration access.
- Review device configuration history for unusual time server entries.
- Check network paths to management interfaces from user and remote segments.
- Document remediation status against VDE-2021-026 guidance.
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-134: 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-2021-33535 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
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://cert.vde.com/en-us/advisories/vde-2021-026CVE 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.
Use of Externally-Controlled Format String
Use of Externally-Controlled Format String represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.