CVE-2026-16366

CRITICALPre-NVD 8.89.8▲
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-21. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.8; sources differ by 1.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.8Exploit: None knownExposed: 0

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

Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS v3
8.8
EG Score
9.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
19%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 24, 2026

Advisory Details (3)

Auto-updated Jul 24, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 153 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-71/
generic

Security Vulnerabilities fixed in Firefox 153 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-68/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2049181

Vendor Advisories for CVE-2026-16366(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 40× in last 7d / 226× 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 285 total refreshes for this CVE.

  1. 2026-08-30 06:11 UTCGHSA enrichment
  2. 2026-08-30 02:23 UTCEG score recompute
  3. 2026-08-30 02:23 UTCGHSA enrichment
  4. 2026-08-30 01:22 UTCEPSS rescore
  5. 2026-08-28 21:41 UTCEPSS rescore
  6. 2026-08-28 01:39 UTCGHSA enrichment
  7. 2026-08-27 21:19 UTCGHSA enrichment
  8. 2026-08-27 15:16 UTCEG score recompute
  9. 2026-08-27 15:16 UTCGHSA enrichment
  10. 2026-08-27 14:25 UTCEPSS rescore
  11. 2026-08-27 11:28 UTCGHSA enrichment
  12. 2026-08-27 01:27 UTCGHSA enrichment
  13. 2026-08-26 21:39 UTCGHSA enrichment
  14. 2026-08-26 15:31 UTCEG score recompute
  15. 2026-08-26 15:31 UTCGHSA enrichment
  16. 2026-08-26 14:46 UTCEPSS rescore
  17. 2026-08-26 11:39 UTCGHSA enrichment
  18. 2026-08-26 07:17 UTCGHSA enrichment
  19. 2026-08-26 02:25 UTCGHSA enrichment
  20. 2026-08-25 22:37 UTCGHSA enrichment
  21. 2026-08-25 18:23 UTCGHSA enrichment
  22. 2026-08-25 14:35 UTCEG score recompute
  23. 2026-08-25 14:35 UTCGHSA enrichment
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-25 10:46 UTCGHSA enrichment
Show 75 more
  1. 2026-08-25 06:44 UTCGHSA enrichment
  2. 2026-08-25 02:46 UTCGHSA enrichment
  3. 2026-08-24 22:57 UTCGHSA enrichment
  4. 2026-08-24 19:09 UTCGHSA enrichment
  5. 2026-08-24 15:19 UTCEG score recompute
  6. 2026-08-24 15:19 UTCGHSA enrichment
  7. 2026-08-24 11:30 UTCEG score recompute
  8. 2026-08-24 11:30 UTCGHSA enrichment
  9. 2026-08-24 07:42 UTCGHSA enrichment
  10. 2026-08-24 03:42 UTCGHSA enrichment
  11. 2026-08-23 23:06 UTCGHSA enrichment
  12. 2026-08-23 19:18 UTCGHSA enrichment
  13. 2026-08-23 15:30 UTCGHSA enrichment
  14. 2026-08-23 11:42 UTCGHSA enrichment
  15. 2026-08-23 07:54 UTCGHSA enrichment
  16. 2026-08-23 04:06 UTCEG score recompute
  17. 2026-08-23 04:06 UTCGHSA enrichment
  18. 2026-08-23 00:19 UTCEPSS rescore
  19. 2026-08-23 00:17 UTCGHSA enrichment
  20. 2026-08-22 20:29 UTCGHSA enrichment
  21. 2026-08-22 16:41 UTCGHSA enrichment
  22. 2026-08-22 12:53 UTCGHSA enrichment
  23. 2026-08-22 09:02 UTCGHSA enrichment
  24. 2026-08-22 05:12 UTCGHSA enrichment
  25. 2026-08-22 01:24 UTCEG score recompute
  26. 2026-08-22 01:24 UTCGHSA enrichment
  27. 2026-08-21 23:49 UTCEPSS rescore
  28. 2026-08-21 21:36 UTCGHSA enrichment
  29. 2026-08-21 17:48 UTCGHSA enrichment
  30. 2026-08-21 14:00 UTCGHSA enrichment
  31. 2026-08-21 09:38 UTCGHSA enrichment
  32. 2026-08-21 05:50 UTCGHSA enrichment
  33. 2026-08-21 02:02 UTCEG score recompute
  34. 2026-08-21 02:02 UTCGHSA enrichment
  35. 2026-08-20 22:55 UTCEPSS rescore
  36. 2026-08-20 22:13 UTCGHSA enrichment
  37. 2026-08-20 18:23 UTCEG score recompute
  38. 2026-08-20 18:23 UTCGHSA enrichment
  39. 2026-08-20 14:34 UTCGHSA enrichment
  40. 2026-08-20 10:24 UTCGHSA enrichment
  41. 2026-08-20 06:36 UTCGHSA enrichment
  42. 2026-08-20 02:47 UTCGHSA enrichment
  43. 2026-08-19 22:45 UTCEG score recompute
  44. 2026-08-19 22:45 UTCGHSA enrichment
  45. 2026-08-19 17:03 UTCEPSS rescore
  46. 2026-08-19 15:35 UTCGHSA enrichment
  47. 2026-08-19 11:48 UTCGHSA enrichment
  48. 2026-08-19 07:38 UTCGHSA enrichment
  49. 2026-08-19 03:50 UTCGHSA enrichment
  50. 2026-08-18 23:21 UTCGHSA enrichment
  51. 2026-08-18 19:34 UTCEG score recompute
  52. 2026-08-18 19:34 UTCGHSA enrichment
  53. 2026-08-18 13:48 UTCEPSS rescore
  54. 2026-08-18 09:37 UTCGHSA enrichment
  55. 2026-08-18 05:49 UTCGHSA enrichment
  56. 2026-08-18 01:43 UTCGHSA enrichment
  57. 2026-08-17 21:03 UTCGHSA enrichment
  58. 2026-08-17 17:15 UTCEG score recompute
  59. 2026-08-17 17:15 UTCGHSA enrichment
  60. 2026-08-17 13:47 UTCEPSS rescore
  61. 2026-08-17 13:27 UTCGHSA enrichment
  62. 2026-08-17 09:39 UTCGHSA enrichment
  63. 2026-08-17 05:51 UTCGHSA enrichment
  64. 2026-08-17 01:24 UTCGHSA enrichment
  65. 2026-08-16 21:36 UTCGHSA enrichment
  66. 2026-08-16 17:48 UTCEG score recompute
  67. 2026-08-16 17:48 UTCGHSA enrichment
  68. 2026-08-16 14:56 UTCEPSS rescore
  69. 2026-08-16 13:40 UTCGHSA enrichment
  70. 2026-08-16 09:51 UTCGHSA enrichment
  71. 2026-08-16 06:03 UTCGHSA enrichment
  72. 2026-08-16 02:15 UTCEG score recompute
  73. 2026-08-16 02:15 UTCGHSA enrichment
  74. 2026-08-16 02:14 UTCEPSS rescore
  75. 2026-08-15 22:28 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-16366?
CVE-2026-16366 is a critical vulnerability published on July 21, 2026. Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
When was CVE-2026-16366 disclosed?
CVE-2026-16366 was first published in the National Vulnerability Database on July 21, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-16366 actively exploited?
CVE-2026-16366 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 81.3% of all scored CVEs.
What is the CVSS score of CVE-2026-16366?
CVE-2026-16366 has a CVSS v3.1 base score of 8.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.8.
How do I remediate CVE-2026-16366?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16366, 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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