CVE-2026-84124

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreHIGH confidence

Score 5.4 from GitHub Security Advisory published 2026-09-01. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — Patch released this week
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

A fix is available — apply it.

Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

CVSS v3
5.4
EG Score
5.4(high)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 2, 2026

Advisory Details (4)

Auto-updated Sep 1, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Firefox ESR 153.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-85/
generic

Security Vulnerabilities fixed in Firefox ESR 140.15 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-84/
generic

Security Vulnerabilities fixed in Firefox 155 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-82/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2061110

Vendor Advisories for CVE-2026-84124(1)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatthunderbird-0:140.16.0-1.el9_82026-09-24redhat

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.

Affected Packages

(6 across 3 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (198 versions)140.15.0esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (227 versions)1:140.15.0esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (74 versions)140.15.0esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (83 versions)1:140.15.0esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (75 versions)140.15.0esr-1—
thunderbird1:128.13.0esr-1 ... 1:153.2.0esr-1 (93 versions)——

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 21× in last 7d / 76× 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.

  1. 2026-09-24 20:01 UTCEG score recompute
  2. 2026-09-24 20:01 UTCVendor advisory
  3. 2026-09-24 20:01 UTCGHSA enrichment
  4. 2026-09-24 14:04 UTCEPSS rescore
  5. 2026-09-23 21:49 UTCEG score recompute
  6. 2026-09-23 21:49 UTCGHSA enrichment
  7. 2026-09-23 17:54 UTCEPSS rescore
  8. 2026-09-22 23:38 UTCEG score recompute
  9. 2026-09-22 23:38 UTCGHSA enrichment
  10. 2026-09-22 16:01 UTCEPSS rescore
  11. 2026-09-22 01:16 UTCEG score recompute
  12. 2026-09-22 01:16 UTCGHSA enrichment
  13. 2026-09-21 21:09 UTCEPSS rescore
  14. 2026-09-21 03:04 UTCEG score recompute
  15. 2026-09-21 03:04 UTCGHSA enrichment
  16. 2026-09-20 20:16 UTCEPSS rescore
  17. 2026-09-20 04:51 UTCEG score recompute
  18. 2026-09-20 04:51 UTCGHSA enrichment
  19. 2026-09-19 06:39 UTCEG score recompute
  20. 2026-09-19 06:39 UTCGHSA enrichment
  21. 2026-09-18 19:28 UTCEPSS rescore
  22. 2026-09-18 08:28 UTCEG score recompute
  23. 2026-09-18 08:28 UTCGHSA enrichment
  24. 2026-09-17 19:32 UTCEPSS rescore
  25. 2026-09-17 10:17 UTCEG score recompute
Show 51 more
  1. 2026-09-17 10:17 UTCGHSA enrichment
  2. 2026-09-16 14:09 UTCEPSS rescore
  3. 2026-09-16 12:06 UTCEG score recompute
  4. 2026-09-16 12:06 UTCGHSA enrichment
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-15 13:54 UTCEG score recompute
  7. 2026-09-15 13:54 UTCGHSA enrichment
  8. 2026-09-15 03:12 UTCEPSS rescore
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-14 15:42 UTCGHSA enrichment
  11. 2026-09-13 17:31 UTCEG score recompute
  12. 2026-09-13 17:31 UTCGHSA enrichment
  13. 2026-09-12 19:20 UTCEG score recompute
  14. 2026-09-12 19:20 UTCGHSA enrichment
  15. 2026-09-11 21:08 UTCEG score recompute
  16. 2026-09-11 21:08 UTCGHSA enrichment
  17. 2026-09-11 14:53 UTCEPSS rescore
  18. 2026-09-11 14:53 UTCEPSS rescore
  19. 2026-09-10 22:57 UTCEG score recompute
  20. 2026-09-10 22:57 UTCGHSA enrichment
  21. 2026-09-10 00:45 UTCGHSA enrichment
  22. 2026-09-09 02:33 UTCEG score recompute
  23. 2026-09-09 02:33 UTCGHSA enrichment
  24. 2026-09-08 22:01 UTCEPSS rescore
  25. 2026-09-08 04:22 UTCEG score recompute
  26. 2026-09-08 04:22 UTCGHSA enrichment
  27. 2026-09-07 06:11 UTCEG score recompute
  28. 2026-09-07 06:10 UTCGHSA enrichment
  29. 2026-09-06 13:48 UTCEPSS rescore
  30. 2026-09-06 07:58 UTCEG score recompute
  31. 2026-09-06 07:58 UTCGHSA enrichment
  32. 2026-09-05 15:31 UTCEPSS rescore
  33. 2026-09-05 09:46 UTCEG score recompute
  34. 2026-09-05 09:46 UTCGHSA enrichment
  35. 2026-09-04 11:35 UTCEG score recompute
  36. 2026-09-04 11:35 UTCGHSA enrichment
  37. 2026-09-04 05:07 UTCEPSS rescore
  38. 2026-09-03 13:22 UTCGHSA enrichment
  39. 2026-09-02 15:07 UTCEG score recompute
  40. 2026-09-02 15:07 UTCGHSA enrichment
  41. 2026-09-02 14:12 UTCEPSS rescore
  42. 2026-09-01 22:20 UTCGHSA enrichment
  43. 2026-09-01 21:43 UTCGHSA enrichment
  44. 2026-09-01 21:09 UTCGHSA enrichment
  45. 2026-09-01 15:40 UTCEG score recompute
  46. 2026-09-01 15:40 UTCGHSA enrichment
  47. 2026-09-01 15:13 UTCEG score recompute▲ 5.40
  48. 2026-09-01 15:12 UTCMITRE cvelistV5CVSS v3 → 5.4 · severity → MEDIUM
  49. 2026-09-01 13:35 UTCNVD update
  50. 2026-09-01 12:45 UTCEG score recompute
  51. 2026-09-01 12:41 UTCMITRE cvelistV5first tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-84124?
CVE-2026-84124 is a medium vulnerability published on September 1, 2026. Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
When was CVE-2026-84124 disclosed?
CVE-2026-84124 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84124 actively exploited?
CVE-2026-84124 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.4% of all scored CVEs.
What is the CVSS score of CVE-2026-84124?
CVE-2026-84124 has a CVSS v3.1 base score of 5.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-84124?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84124, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-84124

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