Security readout for executives and security teams
Plain-English summary
Certain WAGO managed switches have a reflected cross-site scripting flaw in Web-Based Management. An attacker could lure a legitimate user into opening a malicious link, causing code to run in that management context. The reported CVSS score is high, but evidence here does not show active exploitation.
Executive priority
Treat as high priority for environments using the listed WAGO switches, especially operational networks. The business risk is unauthorized action or data exposure through an administrator’s browser, but remediation specifics require vendor guidance because versions and fixes are not detailed in the supplied bundle.
Technical view
CVE-2021-20994 is CWE-79 reflected XSS affecting WAGO managed switch Web-Based Management. CVSS 3.1 is 8.8 with network attack vector, low complexity, no privileges required, and user interaction required. The source bundle lists affected versions as unspecified.
Likely exposure
Exposure is likely where affected WAGO models 0852-0303, 0852-1305, 0852-1505, 0852-1305/000-001, or 0852-1505/000-001 are deployed and their Web-Based Management is reachable by administrators. Version-level exposure is unclear from the provided sources.
Exploitation context
The known scenario requires tricking a legitimate user into clicking a crafted link. The bundle does not include proof of active exploitation, KEV listing, public exploit status, patch details, or specific vulnerable parameters.
Researcher notes
The evidence supports reflected XSS, not unauthenticated device takeover by itself. User interaction is required. Affected version data is incomplete, so testing and prioritization should focus on confirmed model presence, management-plane reachability, and vendor advisory correlation.
Mitigation direction
- Check the VDE/WAGO advisory for affected firmware and vendor remediation guidance.
- Inventory the listed WAGO managed switch models across operational networks.
- Restrict Web-Based Management to trusted administrative networks where feasible.
- Avoid exposing management interfaces to untrusted networks or general user segments.
- Warn administrators against opening unsolicited links while authenticated to management portals.
Validation and detection
- Confirm whether any listed WAGO switch models are present in asset inventory.
- Record firmware versions and compare them with vendor advisory guidance.
- Verify who can reach each switch Web-Based Management interface.
- Review management access logs for unusual administrator sessions or suspicious referrers.
- Document unresolved exposure where version details remain unavailable.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2021-20994 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: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:N/AC:L/PR:N/UI:R/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:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://cert.vde.com/en-us/advisories/vde-2021-013CVE 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 Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.