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Homelynk Firmware CVE-2021-22737

CRITICAL
Improper Restriction of Excessive Authentication Attempts (CWE-307)
2021-05-26 cybersecurity@se.com
Authentication Bypass Schneider Electric Homelynk Firmware Spacelynk Firmware
9.8
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-307
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Brute-force prevention, rate limiting
Impact

CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the critical-severity affected system.
Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.9% exploitation probability (EPSS)

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AnalysisAI

Insufficiently Protected Credentials vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior that could cause unauthorized access of when credentials are discovered after a. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

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Technical ContextAI · show details

This vulnerability is classified under CWE-307. Insufficiently Protected Credentials vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior that could cause unauthorized access of when credentials are discovered after a brute force attack. Affected products include: Schneider-Electric Spacelynk Firmware, Schneider-Electric Homelynk Firmware.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionNVD

Insufficiently Protected Credentials vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior that could cause unauthorized access of when credentials are discovered after a brute force attack.

Threat Intelligence Overview

EPSS Score
0.9%
Top 43% exploitable
Data Quality
2 sources
Confidence: Low
NVD CVE.org EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.9%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

50
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)NVD

cpe:2.3:o:schneider-electric:spacelynk_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:schneider-electric:homelynk_firmware:*:*:*:*:*:*:*:*

More in Homelynk Firmware

View all
CVE-2021-22738 CRITICAL
9.8 May 26

Use of a Broken or Risky Cryptographic Algorithm vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 an
CVE-2021-22733 HIGH
7.8 May 26

Improper Privilege Management vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior which could
CVE-2021-22732 HIGH
7.8 May 26

Improper Privilege Management vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior which could
CVE-2021-22736 HIGH
7.5 May 26

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability exists in homeLYnk (Wiser F
CVE-2018-7779 HIGH
7.5 Jul 03

In Schneider Electric Wiser for KNX V2.1.0 and prior, homeLYnk V2.0.1 and prior; and spaceLYnk V2.1.0 and prior, weak an
CVE-2021-22735 HIGH
7.2 May 26

Improper Verification of Cryptographic Signature vulnerability exists inhomeLYnk (Wiser For KNX) and spaceLYnk V2.60 and
CVE-2021-22734 HIGH
7.2 May 26

Improper Verification of Cryptographic Signature vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 an
CVE-2021-22740 MEDIUM
6.5 May 26

Information Exposure vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior which could cause in
CVE-2021-22739 MEDIUM
5.9 May 26

Information Exposure vulnerability exists in homeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior which could cause a

Same weakness CWE-307 – Improper Restriction of Excessive Authentication Attempts

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References

Advisories & patches
ADVISORY https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2021-130-04

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