CVE-2026-93866

CRITICALPre-NVD 9.29.2
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (43rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source

Also known asEUVD-2026-111157 (ENISA EUVD) · GHSA-g944-9gh9-2wqp (GitHub Security Advisories)Source: ENISA EUVD

9.2EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.2Exploit: None knownExposed services: Not assessed

Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22 (from the CVE record's solution, WatchGuard Technologies, Inc.) — apply it.

An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.

CVSS
9.2
EG Score
9.2CRITICALmedium confidence
EG Risk
42
EG Risk 42/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity92% × 45%
Impact severity (EG Severity): CVSS 9.2 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22 (from the CVE record's solution, WatchGuard Technologies, Inc.). Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
43rd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.2): severity, escalated by confirmed exploitation. This CVE's 9.2 is its impact severity (EG Severity), not escalated.

EG Severity
9.2 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22 (from the CVE record's solution, WatchGuard Technologies, Inc.). Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 27, 2026

Last Modified

November 4, 2026

Advisory Details (1)

Auto-updated Oct 27, 2026
Fix named in the CVE record's solution (WatchGuard Technologies, Inc.).
Web page

CVE-2026-93866 — Fireware OS Pre-Authentication Integer Overflow in Access Portal Allows Out-of-Bounds Write

https://psirt.watchguard.com/CVE-2026-93866

Vendor Advisories for CVE-2026-93866(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 38× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

  1. 2026-11-13 01:10 UTCEchelonGraph re-scored
  2. 2026-11-13 01:10 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  3. 2026-11-12 16:35 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  4. 2026-11-12 01:55 UTCEchelonGraph re-scored
  5. 2026-11-12 01:55 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  6. 2026-11-11 16:41 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  7. 2026-11-11 02:44 UTCEchelonGraph re-scored
  8. 2026-11-11 02:44 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  9. 2026-11-10 16:46 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  10. 2026-11-10 16:34 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  11. 2026-11-09 17:21 UTCEchelonGraph re-scored
  12. 2026-11-09 17:21 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  13. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-11-08 18:10 UTCEchelonGraph re-scored
  15. 2026-11-08 18:10 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  16. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  17. 2026-11-07 19:00 UTCEchelonGraph re-scored
  18. 2026-11-07 19:00 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  19. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  20. 2026-11-06 19:48 UTCEchelonGraph re-scored
  21. 2026-11-06 19:48 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  22. 2026-11-06 16:40 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  23. 2026-11-05 20:37 UTCEchelonGraph re-scored
  24. 2026-11-05 20:37 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  25. 2026-11-05 16:39 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
Show 33 more
  1. 2026-11-04 21:26 UTCEchelonGraph re-scored
  2. 2026-11-04 21:26 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  3. 2026-11-04 20:36 UTCEchelonGraph re-scored
  4. 2026-11-04 20:36 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  5. 2026-11-04 17:37 UTCEchelonGraph re-scored
  6. 2026-11-04 17:37 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  7. 2026-11-04 16:37 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  8. 2026-11-03 18:25 UTCEchelonGraph re-scored
  9. 2026-11-03 18:25 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  10. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  11. 2026-11-03 09:54 UTCEchelonGraph re-scored
  12. 2026-11-03 09:54 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  13. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  14. 2026-11-02 10:43 UTCEchelonGraph re-scored
  15. 2026-11-02 10:42 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  16. 2026-11-01 16:36 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  17. 2026-11-01 11:31 UTCEchelonGraph re-scored
  18. 2026-11-01 11:31 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  19. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.4% · 39th percentile
  20. 2026-10-31 12:21 UTCEchelonGraph re-scored
  21. 2026-10-31 12:21 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  22. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  23. 2026-10-30 13:10 UTCEchelonGraph re-scored
  24. 2026-10-30 13:10 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  25. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  26. 2026-10-29 13:59 UTCEchelonGraph re-scored
  27. 2026-10-29 13:59 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  28. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.4% · 38th percentile
  29. 2026-10-28 14:47 UTCGHSA enrichmentGHSA-g944-9gh9-2wqp · GitHub severity CRITICAL
  30. 2026-10-27 17:01 UTCENISA EUVD ID recordedEUVD-2026-111157 · Source: ENISA EUVD
  31. 2026-10-27 16:29 UTCEchelonGraph re-scored
  32. 2026-10-27 16:04 UTCEchelonGraph re-scoredFirst assessed: 9.2 CRITICAL
  33. 2026-10-27 15:59 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-93866?
CVE-2026-93866 is a critical-severity vulnerability; its CVE record was published on October 27, 2026. An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.
When was the CVE record for CVE-2026-93866 published?
The CVE record for CVE-2026-93866 was published on October 27, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of November 4, 2026; the record at its source may have been updated since.
Is CVE-2026-93866 actively exploited?
CVE-2026-93866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (43rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-93866?
CVE-2026-93866 has a CVSS base score of 9.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-93866?
The CVE record's solution for CVE-2026-93866, written by its CNA WatchGuard Technologies, Inc., names the fix: "Fireware OS 2026.4, Fireware OS 12.12.4, Fireware OS 12.5.22". The vendor advisories EchelonGraph has for CVE-2026-93866 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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