Evidence used
- No CISA KEV confirmation is currently recorded.
- EPSS is 0.95% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2021-25667High confidence
Siemens RUGGEDCOM RM1224 — Stack-based Buffer Overflow
Siemens · RUGGEDCOM RM1224
8.8HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Siemens RUGGEDCOM RM1224 and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Siemens ProductCERT: 11 affected or under-investigation product states without a fixed product state in the same current advisory
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
SSA-979775 · CSAF 2.0 · revision 2 · finalSiemens ProductCERTSSA-979775: Stack Overflow Vulnerability in SCALANCE and RUGGEDCOM Devices
The vendor explicitly identifies these products as affected by this CVE.
- RUGGEDCOM RM1224
- SCALANCE M-800
- SCALANCE S615
- SCALANCE SC-600 Family
- SCALANCE XB-200
- SCALANCE XC-200
- SCALANCE XF-200BA
- SCALANCE XM400
- SCALANCE XP-200
- SCALANCE XR500
- SCALANCE XR-300WG
- Summary
- Affected devices contain a stack-based buffer overflow vulnerability in the handling of STP BPDU frames that could allow a remote attacker to trigger a denial-of-service condition or potentially remote code execution. Successful exploitation requires the passive listening feature of the device to be active.
- Remediation
- Update to V6.4 or later version
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 11 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
A vulnerability has been identified in RUGGEDCOM RM1224 (All versions >= V4.3 and < V6.4), SCALANCE M-800 (All versions >= V4.3 and < V6.4), SCALANCE S615 (All versions >= V4.3 and < V6.4), SCALANCE SC-600 Family (All versions >= V2.0 and < V2.1.3), SCALANCE XB-200 (All versions < V4.1), SCALANCE XC-200 (All versions < V4.1), SCALANCE XF-200BA (All versions < V4.1), SCALANCE XM400 (All versions < V6.2), SCALANCE XP-200 (All versions < V4.1), SCALANCE XR-300WG (All versions < V4.1), SCALANCE XR500 (All versions < V6.2). Affected devices contain a stack-based buffer overflow vulnerability in the handling of STP BPDU frames that could allow a remote attacker to trigger a denial-of-service condition or potentially remote code execution. Successful exploitation requires the passive listening feature of the device to be active.
What
A vulnerability has been identified in RUGGEDCOM RM1224 (All versions >= V4.3 and < V6.4), SCALANCE M-800 (All versions >= V4.3 and < V6.4), SCALANCE S615 (All versions >= V4.3 and < V6.4), SCALANCE SC-600 Family (All versions >= V2.0 and < V2.1.3), SCALANCE XB-200 (All versions < V4.1), SCALANCE XC-200 (All versions < V4.1), SCALANCE XF-200BA (All versions < V4.1), SCALANCE XM400 (All versions < V6.2), SCALANCE XP-200 (All versions < V4.1), SCALANCE XR-300WG (All versions < V4.1), SCALANCE XR500 (All versions < V6.2). Affected devices contain a stack-based buffer overflow vulnerability in the handling of STP BPDU frames that could allow a remote attacker to trigger a denial-of-service condition or potentially remote code execution. Successful exploitation requires the passive listening feature of the device to be active.
Why
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
How
An attacker operating through the affected interface may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
What
A vulnerability has been identified in RUGGEDCOM RM1224 (All versions >= V4.3 and < V6.4), SCALANCE M-800 (All versions >= V4.3 and < V6.4), SCALANCE S615 (All versions >= V4.3 and < V6.4), SCALANCE SC-600 Family (All versions >= V2.0 and < V2.1.3), SCALANCE XB-200 (All versions < V4.1), SCALANCE XC-200 (All versions < V4.1), SCALANCE XF-200BA (All versions < V4.1), SCALANCE XM400 (All versions < V6.2), SCALANCE XP-200 (All versions < V4.1), SCALANCE XR-300WG (All versions < V4.1), SCALANCE XR500 (All versions < V6.2). Affected devices contain a stack-based buffer overflow vulnerability in the handling of STP BPDU frames that could allow a remote attacker to trigger a denial-of-service condition or potentially remote code execution. Successful exploitation requires the passive listening feature of the device to be active.
Why
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
How
An attacker operating through the affected interface may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- the affected interface → Stack-based Buffer Overflow → execute code or commands in the affected security context
- Attack surface
- Unspecified
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-121 ↗
CWE-121: Stack-based Buffer Overflow. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVAdjacentAttack vector: The attacker must be on an adjacent or logically close network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Fix availability varies by product
- Affected
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 15 Mar 2021 · Last source change 2 Jun 2026, 19:24 UTC · CWE-121 · Stack-based Buffer Overflow
CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-12559
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Remediation statusRemediation status changed from Patch available to Mitigation available.Siemens ProductCERT ↗
- Before
- Patch available
- After
- Mitigation available
CVE published
Fixed release or patch reference recorded
Remediation guidance recorded
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.