CVE-2026-16399

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-21. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

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

Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 24, 2026

Advisory Details (2)

Auto-updated Jul 22, 2026
No patch confirmed yet.
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=2049981

Vendor Advisories for CVE-2026-16399(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 17× in last 7d / 91× 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 192 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-16399?
CVE-2026-16399 is a high vulnerability published on July 21, 2026. Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
When was CVE-2026-16399 disclosed?
CVE-2026-16399 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-2026-16399 actively exploited?
CVE-2026-16399 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 95.6% of all scored CVEs.
What is the CVSS score of CVE-2026-16399?
CVE-2026-16399 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-16399?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16399, 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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