CVE-2026-84139

MEDIUMNVD 6.16.1—
EchelonGraph scoreHIGH confidence

Score 6.1 from GitHub Security Advisory published 2026-09-01. NVD baseline CVSS 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
6.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.1Exploit: None knownExposed: 0

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

Clickjacking issue in the DOM: Events component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

CVSS v3
6.1
EG Score
6.1(high)
EG Risk
43(Track)
EG Risk 43/100SSVC: 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
Severity61% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
8%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 3, 2026

Advisory Details (5)

Auto-updated Sep 3, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 153.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-88/
generic

Security Vulnerabilities fixed in Thunderbird 155 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-86/
generic

Security Vulnerabilities fixed in Firefox ESR 153.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-85/
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=2060153

Vendor Advisories for CVE-2026-84139(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 18× in last 7d / 55× 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. 2026-09-18 23:49 UTCEG score recompute
  2. 2026-09-18 23:49 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 21:46 UTCEG score recompute
  5. 2026-09-17 21:46 UTCGHSA enrichment
  6. 2026-09-17 19:32 UTCEPSS rescore
  7. 2026-09-16 19:42 UTCEG score recompute
  8. 2026-09-16 19:42 UTCGHSA enrichment
  9. 2026-09-16 14:09 UTCEPSS rescore
  10. 2026-09-16 05:15 UTCEPSS rescore
  11. 2026-09-15 17:37 UTCEG score recompute
  12. 2026-09-15 17:37 UTCGHSA enrichment
  13. 2026-09-15 03:12 UTCEPSS rescore
  14. 2026-09-15 03:12 UTCEPSS rescore
  15. 2026-09-14 15:33 UTCEG score recompute
  16. 2026-09-14 15:33 UTCGHSA enrichment
  17. 2026-09-13 13:29 UTCEG score recompute
  18. 2026-09-13 13:29 UTCGHSA enrichment
  19. 2026-09-12 11:25 UTCEG score recompute
  20. 2026-09-12 11:25 UTCGHSA enrichment
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-11 14:53 UTCEPSS rescore
  23. 2026-09-11 09:21 UTCEG score recompute
  24. 2026-09-11 09:21 UTCGHSA enrichment
  25. 2026-09-10 07:17 UTCGHSA enrichment
Show 30 more
  1. 2026-09-09 05:12 UTCEG score recompute
  2. 2026-09-09 05:12 UTCGHSA enrichment
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-08 03:09 UTCEG score recompute
  5. 2026-09-08 03:09 UTCGHSA enrichment
  6. 2026-09-07 01:05 UTCEG score recompute
  7. 2026-09-07 01:05 UTCGHSA enrichment
  8. 2026-09-06 13:48 UTCEPSS rescore
  9. 2026-09-05 22:59 UTCEG score recompute
  10. 2026-09-05 22:58 UTCGHSA enrichment
  11. 2026-09-05 15:31 UTCEPSS rescore
  12. 2026-09-04 20:55 UTCEG score recompute
  13. 2026-09-04 20:54 UTCGHSA enrichment
  14. 2026-09-04 05:07 UTCEPSS rescore
  15. 2026-09-03 18:46 UTCEG score recompute
  16. 2026-09-03 18:45 UTCGHSA enrichment
  17. 2026-09-03 17:35 UTCEG score recompute
  18. 2026-09-03 17:35 UTCGHSA enrichment
  19. 2026-09-03 16:36 UTCEG score recompute▲ 6.10
  20. 2026-09-03 16:36 UTCGHSA enrichment
  21. 2026-09-03 16:35 UTCNVD updateCVSS v3 → 6.1 · severity → MEDIUM
  22. 2026-09-02 14:12 UTCEPSS rescore
  23. 2026-09-01 22:19 UTCGHSA enrichment
  24. 2026-09-01 22:18 UTCNVD update
  25. 2026-09-01 21:43 UTCGHSA enrichment
  26. 2026-09-01 21:42 UTCMITRE cvelistV5
  27. 2026-09-01 21:08 UTCGHSA enrichment
  28. 2026-09-01 13:35 UTCNVD update
  29. 2026-09-01 12:44 UTCEG score recompute
  30. 2026-09-01 12:41 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-84139?
CVE-2026-84139 is a medium vulnerability published on September 1, 2026. Clickjacking issue in the DOM: Events component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
When was CVE-2026-84139 disclosed?
CVE-2026-84139 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 3, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84139 actively exploited?
CVE-2026-84139 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 92.2% of all scored CVEs.
What is the CVSS score of CVE-2026-84139?
CVE-2026-84139 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-84139?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84139, 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

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