Security readout for executives and security teams
Plain-English summary
CVE-2021-33536 can let an unauthenticated network attacker crash affected Weidmüller industrial WLAN devices. The business impact is availability: wireless connectivity used in industrial environments may be disrupted until the device recovers or is restored.
Executive priority
Treat as high priority for industrial sites that depend on these WLAN devices for operations. The vulnerability does not indicate data theft, but it can disrupt network availability without authentication.
Technical view
The issue is an integer underflow in ServiceAgent functionality. A crafted network packet can trigger an oversized memcpy that reaches unmapped or out-of-bounds memory, causing denial of service. CVSS 3.1 is 7.5: network reachable, low complexity, no privileges, no user interaction, availability impact only.
Likely exposure
Exposure is most likely where the listed Weidmüller IE-WL(T)-BL-AP-CL-XX or IE-WL(T)-VL-AP-CL-XX industrial WLAN devices are deployed and reachable by untrusted network traffic. Organizations without these models, or with tightly isolated device access, have lower exposure.
Exploitation context
The source states unauthenticated network triggering is possible, but the provided bundle does not cite public exploitation. CISA KEV status is false, so active exploitation should not be claimed from this evidence.
Researcher notes
Evidence supports CWE-191 integer underflow leading to denial of service through ServiceAgent. The bundle does not provide packet details, fixed versions, or confirmed exploitation, so validation should remain inventory- and exposure-focused.
Mitigation direction
- Identify whether listed Weidmüller WLAN models are deployed.
- Check the VDE/Weidmüller advisory for vendor-supported fixes or mitigations.
- Restrict untrusted network reachability to affected device services.
- Prioritize compensating controls for production WLAN segments.
- Track vendor guidance before making firmware or configuration changes.
Validation and detection
- Inventory model numbers against the affected product list.
- Confirm whether ServiceAgent-facing traffic is reachable from untrusted networks.
- Review device logs for unexplained restarts or availability events.
- Verify implemented controls match current vendor advisory guidance.
- Document exposed units and operational dependency on their WLAN service.
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-191: 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 lookupCVE-2021-33536 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
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.
Integer Underflow (Wrap or Wraparound)
Integer Underflow (Wrap or Wraparound) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.