CVE-2026-16406

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-21. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

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

Mitigation bypass in the Networking component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 22, 2026

Advisory Details (3)

Auto-updated Sep 7, 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=2040382

Vendor Advisories for CVE-2026-16406(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 25× in last 7d / 164× 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 464 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-16406?
CVE-2026-16406 is a critical vulnerability published on July 21, 2026. Mitigation bypass in the Networking component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
When was CVE-2026-16406 disclosed?
CVE-2026-16406 was first published in the National Vulnerability Database on July 21, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-16406 actively exploited?
CVE-2026-16406 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 83.6% of all scored CVEs.
What is the CVSS score of CVE-2026-16406?
CVE-2026-16406 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-16406?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16406, 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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