CVE-2023-6866

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2023-12-19. NVD baseline CVSS 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.8Exploit: None knownExposed: 0

A fix is available — apply it.

TypedArrays can be fallible and lacked proper exception handling. This could lead to abuse in other APIs which expect TypedArrays to always succeed. This vulnerability affects Firefox < 121.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: 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
Severity88% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
51%
KEV
Not listed

Published

December 19, 2023

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 30, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Firefox 121 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2023-56/
generic

Mozilla Firefox: Multiple Vulnerabilities (GLSA 202401-10) — Gentoo security

https://security.gentoo.org/glsa/202401-10
generic

1849037 - (CVE-2023-6866) Many uses of TypedArray::Create don't handle failures correctly

https://bugzilla.mozilla.org/show_bug.cgi?id=1849037

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntufirefox-mozsymbols (121.0+build1-0ubuntu0.20.04.1) @ focal2026-05-24ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 6× in last 7d / 28× 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 153 total refreshes for this CVE.

  1. 2026-09-18 19:26 UTCEPSS rescore
  2. 2026-09-16 14:06 UTCEPSS rescore
  3. 2026-09-16 05:11 UTCEPSS rescore
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  1. 2026-08-23 00:17 UTCEPSS rescore
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  24. 2026-07-30 16:26 UTCEPSS rescore
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  26. 2026-07-28 15:34 UTCEPSS rescore
  27. 2026-07-28 15:34 UTCEPSS rescore
  28. 2026-07-26 14:53 UTCEPSS rescore
  29. 2026-07-25 14:16 UTCEPSS rescore
  30. 2026-07-24 14:16 UTCEPSS rescore
  31. 2026-07-23 14:16 UTCEPSS rescore
  32. 2026-07-23 02:30 UTCEG score recompute
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  40. 2026-07-19 02:27 UTCEPSS rescore
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  45. 2026-07-15 16:56 UTCEPSS rescore
  46. 2026-07-15 01:59 UTCEPSS rescore
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  48. 2026-07-13 22:28 UTCEPSS rescore
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  50. 2026-07-13 06:11 UTCEPSS rescore
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  53. 2026-07-11 08:26 UTCEPSS rescore
  54. 2026-07-09 19:08 UTCEPSS rescore
  55. 2026-07-08 15:13 UTCEPSS rescore
  56. 2026-07-07 13:45 UTCEPSS rescore
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  72. 2026-06-25 13:48 UTCEPSS rescore
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  74. 2026-06-24 14:04 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2023-6866?
CVE-2023-6866 is a high vulnerability published on December 19, 2023. TypedArrays can be fallible and lacked proper exception handling. This could lead to abuse in other APIs which expect TypedArrays to always succeed. This vulnerability affects Firefox < 121.
When was CVE-2023-6866 disclosed?
CVE-2023-6866 was first published in the National Vulnerability Database on December 19, 2023, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-6866 actively exploited?
CVE-2023-6866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 49.0% of all scored CVEs.
What is the CVSS score of CVE-2023-6866?
CVE-2023-6866 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2023-6866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-6866, 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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