CVE-2021-40866

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 1.8%, top 24% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 2%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Certain NETGEAR smart switches are affected by a remote admin password change by an unauthenticated attacker via the (disabled by default) /sqfs/bin/sccd daemon, which fails to check authentication when the authentication TLV is missing from a received NSDP packet. This affects GC108P before 1.0.8.2, GC108PP before 1.0.8.2, GS108Tv3 before 7.0.7.2, GS110TPP before 7.0.7.2, GS110TPv3 before 7.0.7.2, GS110TUP before 1.0.5.3, GS308T before 1.0.3.2, GS310TP before 1.0.3.2, GS710TUP before 1.0.5.3, GS716TP before 1.0.4.2, GS716TPP before 1.0.4.2, GS724TPP before 2.0.6.3, GS724TPv2 before 2.0.6.3, GS728TPPv2 before 6.0.8.2, GS728TPv2 before 6.0.8.2, GS750E before 1.0.1.10, GS752TPP before 6.0.8.2, GS752TPv2 before 6.0.8.2, MS510TXM before 1.0.4.2, and MS510TXUP before 1.0.4.2.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
75.6%
KEV
Not listed

Published

September 13, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Jun 18, 2026
No patch confirmed yet.
generic

Security Advisory for Multiple Vulnerabilities on Some Smart Switches, PSV-2021-0140, PSV-2021-0144, PSV-2021-0145 - NETGEAR Support

https://kb.netgear.com/000063978/Security-Advisory-for-Multiple-Vulnerabilities-on-Some-Smart-Switches-PSV-2021-0140-PSV-2021-0144-PSV-2021-0145
generic

Demon's Cries vulnerability (some NETGEAR smart switches) - gynvael.coldwind//vx.log

https://gynvael.coldwind.pl/?id=740

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 47× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 107 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 14:16 UTCEPSS rescore
  3. 2026-07-23 02:04 UTCEG score recompute
  4. 2026-07-22 22:50 UTCEG score recompute▲ 1.00
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Frequently asked(5)

What is CVE-2021-40866?
CVE-2021-40866 is a critical vulnerability published on September 13, 2021. Certain NETGEAR smart switches are affected by a remote admin password change by an unauthenticated attacker via the (disabled by default) /sqfs/bin/sccd daemon, which fails to check authentication when the authentication TLV is missing from a received NSDP packet. This affects GC108P before…
When was CVE-2021-40866 disclosed?
CVE-2021-40866 was first published in the National Vulnerability Database on September 13, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-40866 actively exploited?
CVE-2021-40866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 75.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-40866?
CVE-2021-40866 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-40866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40866, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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