Security readout for executives and security teams
Plain-English summary
This flaw affects multiple Siemens RUGGEDCOM and SCALANCE industrial networking devices. A nearby network attacker could crash an affected device, and the advisory notes possible remote code execution. The issue only applies when the device’s passive listening feature is active.
Executive priority
Treat as a moderate operational resilience issue. Prioritize remediation for production, safety-adjacent, or hard-to-access industrial networks because the main proven impact is denial of service on network infrastructure.
Technical view
CVE-2021-25667 is a CWE-121 stack-based buffer overflow in handling STP BPDU frames. It is unauthenticated, requires adjacent network access, and needs no user interaction. CVSS v3.1 is 6.5 with high availability impact. Successful exploitation requires passive listening to be active.
Likely exposure
Exposure is most likely in industrial or operational networks using the listed Siemens RUGGEDCOM RM1224 or SCALANCE device families on vulnerable firmware, with passive listening enabled and attacker access to the same Layer 2 network path.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. Exploitation is constrained by adjacent-network access and the passive listening prerequisite, but successful attacks could disrupt network availability and may allow remote code execution.
Researcher notes
Focus validation on firmware range, passive listening state, and Layer 2 reachability. The public description names possible RCE but does not provide exploit confirmation in the supplied sources, so avoid assuming code execution in risk scoring.
Mitigation direction
- Upgrade affected devices to Siemens-recommended fixed firmware for the specific product family.
- Disable passive listening where it is not operationally required.
- Restrict Layer 2 access to devices that can send STP BPDU frames.
- Review Siemens and CISA advisories for product-specific remediation guidance.
- Prioritize operational segments where outage would affect safety or production.
Validation and detection
- Inventory listed RUGGEDCOM and SCALANCE models and record firmware versions.
- Check whether passive listening is enabled on each affected device.
- Confirm firmware is outside the vulnerable version ranges in the advisory.
- Validate untrusted hosts cannot reach the relevant Layer 2 segment.
- Review logs or monitoring for unexplained device resets or availability loss.
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-2021-25667 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
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/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.
SSVC decision data
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:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.83.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://cert-portal.siemens.com/productcert/pdf/ssa-979775.pdfCVE reference, siemens · x_refsource_MISC
- https://us-cert.cisa.gov/ics/advisories/icsa-21-068-03CVE reference, siemens · 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.