CVE-2021-25676
No exploitation reported by the sources we read.
- Published2021-03-15
- WeaknessCWE-307
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
A 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.
Timeline
dates in UTC- 2021-03-1517:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-25676?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-25676?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.3 | = 6.3 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.3 | = 6.3 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.3 | = 6.3 | no fix published | NVD |
1 more product in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
Siemens SCALANCE and RUGGEDCOM Devices SSH (Update A)
RUGGEDCOM RM1224 · SCALANCE M-800 · SCALANCE S615 · +1 more
Fix
- Vendor fix CISA ICSA-21-068-02 · 3 productsUpdate to V6.4 or later version
- Vendor fix CISA ICSA-21-068-02 · 1 productUpdate to V2.1.3 or later version
- Mitigation from the vendor CISA ICSA-21-068-02 · 4 productsConfigure the built-in firewall to only allow SSH incoming connections from trusted IP addresses
Advisories and patches
- cert-portal.siemens.comVendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- NVDCVSS 3.17.5read 2026-10-23
- NVDCVSS 2.05read 2026-10-23
- CNAweakness (CWE)CWE-307read 2026-10-23
- FIRST EPSSEPSS score1.3 %2026-10-22
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2021-03-15
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-25676?
Is CVE-2021-25676 actively exploited?
What is the CVSS score for CVE-2021-25676?
Running RUGGEDCOM RM1224 (V6.3)? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.