CVE-2021-25676
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability has been identified in RUGGEDCOM RM1224 (V6.3), SCALANCE M-800 (V6.3), SCALANCE S615 (V6.3), SCALANCE SC-600 (All Versions >= V2.1 and < V2.1.3). Multiple failed SSH authentication attempts could trigger a temporary Denial-of-Service under certain conditions. When triggered, the device will reboot automatically.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceMultiple failed SSH authentication attempts on affected RUGGEDCOM and SCALANCE devices trigger an automatic device reboot, causing temporary denial of service. The vulnerability stems from improper handling of authentication failure conditions that leads to system instability requiring a reboot to recover.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 6.3= 6.3= 6.3>= 2.1, < 2.1.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify device modelAccess the device web interface, CLI, or physical label to determine the exact model (Ruggedcom Rm1224, Scalance M-800, Scalance S615, or Scalance SC-600)Affected if Device is one of these four models listed in affected products
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Check firmware versionAccess device management interface (web UI or CLI) and navigate to system information or firmware version section. Common CLI command: 'show version' or 'system info'Affected if Firmware version is exactly 6.3 for Rm1224/M-800/S615, or between 2.1 and 2.1.2 for SC-600 (inclusive of 2.1, 2.1.1, 2.1.2)
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Verify SSH service is enabledCheck device configuration for SSH server settings. In CLI: 'show running-config' or 'show ssh' to see if SSH service is active and configuredAffected if SSH is enabled and accessible on the device (the vulnerability triggers via failed SSH authentication attempts)
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Review system logs for reboot eventsCheck device logs for unexpected reboots or authentication failure messages. In CLI: 'show log' or 'show system logs' looking for patterns like 'authentication failed' or 'reboot'Affected if Multiple authentication failures followed by reboot events are logged, indicating the vulnerability may have been triggered
Device is affected if it is a Rm1224, M-800, S615 at firmware version 6.3, or SC-600 at firmware versions 2.1 through 2.1.2, and SSH service is enabled.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data2.1.3
Update firmware to vendor-supplied patched versions (V6.3.1 or later for RM1224/M-800/S615; V2.1.3 or later for SCALANCE SC-600). Consider implementing network-level SSH access controls or rate limiting as a compensating control until patches can be applied.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25676 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-25676 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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