CVE-2026-16403

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory published 2026-07-21. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 5 sources updated this week
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0

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

Spoofing issue in the Address Bar component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
3.2%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 22, 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=1972244

Vendor Advisories for CVE-2026-16403(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 102× in last 7d / 102× 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 102 total refreshes for this CVE.

  1. 2026-07-23 03:05 UTCEG score recompute
  2. 2026-07-22 23:11 UTCEG score recompute
  3. 2026-07-22 23:11 UTCGHSA enrichment
  4. 2026-07-22 17:36 UTCEG score recompute▲ 6.50
  5. 2026-07-22 17:36 UTCGHSA enrichment
  6. 2026-07-22 17:35 UTCMITRE cvelistV5CVSS v3 → 6.5 · severity → MEDIUM
  7. 2026-07-22 14:08 UTCEPSS rescore
  8. 2026-07-21 19:12 UTCGHSA enrichment
  9. 2026-07-21 19:12 UTCGHSA enrichment
  10. 2026-07-21 19:10 UTCGHSA enrichment
  11. 2026-07-21 19:09 UTCGHSA enrichment
  12. 2026-07-21 19:07 UTCGHSA enrichment
  13. 2026-07-21 19:04 UTCGHSA enrichment
  14. 2026-07-21 18:58 UTCGHSA enrichment
  15. 2026-07-21 18:40 UTCGHSA enrichment
  16. 2026-07-21 18:38 UTCGHSA enrichment
  17. 2026-07-21 18:35 UTCGHSA enrichment
  18. 2026-07-21 18:34 UTCGHSA enrichment
  19. 2026-07-21 18:31 UTCGHSA enrichment
  20. 2026-07-21 18:28 UTCGHSA enrichment
  21. 2026-07-21 18:26 UTCGHSA enrichment
  22. 2026-07-21 18:24 UTCGHSA enrichment
  23. 2026-07-21 18:20 UTCGHSA enrichment
  24. 2026-07-21 18:15 UTCGHSA enrichment
  25. 2026-07-21 18:14 UTCGHSA enrichment
Show 75 more
  1. 2026-07-21 18:12 UTCGHSA enrichment
  2. 2026-07-21 18:08 UTCGHSA enrichment
  3. 2026-07-21 18:07 UTCGHSA enrichment
  4. 2026-07-21 18:06 UTCGHSA enrichment
  5. 2026-07-21 17:57 UTCGHSA enrichment
  6. 2026-07-21 17:55 UTCGHSA enrichment
  7. 2026-07-21 17:55 UTCGHSA enrichment
  8. 2026-07-21 17:50 UTCGHSA enrichment
  9. 2026-07-21 17:49 UTCGHSA enrichment
  10. 2026-07-21 17:47 UTCGHSA enrichment
  11. 2026-07-21 17:44 UTCGHSA enrichment
  12. 2026-07-21 17:42 UTCGHSA enrichment
  13. 2026-07-21 17:34 UTCGHSA enrichment
  14. 2026-07-21 17:30 UTCGHSA enrichment
  15. 2026-07-21 17:29 UTCGHSA enrichment
  16. 2026-07-21 17:14 UTCGHSA enrichment
  17. 2026-07-21 17:13 UTCGHSA enrichment
  18. 2026-07-21 17:12 UTCGHSA enrichment
  19. 2026-07-21 17:08 UTCGHSA enrichment
  20. 2026-07-21 17:08 UTCGHSA enrichment
  21. 2026-07-21 17:03 UTCGHSA enrichment
  22. 2026-07-21 17:02 UTCGHSA enrichment
  23. 2026-07-21 17:00 UTCGHSA enrichment
  24. 2026-07-21 16:59 UTCGHSA enrichment
  25. 2026-07-21 16:57 UTCGHSA enrichment
  26. 2026-07-21 16:53 UTCGHSA enrichment
  27. 2026-07-21 16:52 UTCGHSA enrichment
  28. 2026-07-21 16:51 UTCGHSA enrichment
  29. 2026-07-21 16:48 UTCGHSA enrichment
  30. 2026-07-21 16:47 UTCGHSA enrichment
  31. 2026-07-21 16:47 UTCGHSA enrichment
  32. 2026-07-21 16:46 UTCGHSA enrichment
  33. 2026-07-21 16:45 UTCGHSA enrichment
  34. 2026-07-21 16:42 UTCGHSA enrichment
  35. 2026-07-21 16:40 UTCGHSA enrichment
  36. 2026-07-21 16:38 UTCGHSA enrichment
  37. 2026-07-21 16:36 UTCGHSA enrichment
  38. 2026-07-21 16:33 UTCGHSA enrichment
  39. 2026-07-21 16:32 UTCGHSA enrichment
  40. 2026-07-21 16:31 UTCGHSA enrichment
  41. 2026-07-21 16:28 UTCGHSA enrichment
  42. 2026-07-21 16:26 UTCGHSA enrichment
  43. 2026-07-21 16:25 UTCGHSA enrichment
  44. 2026-07-21 16:22 UTCGHSA enrichment
  45. 2026-07-21 16:19 UTCGHSA enrichment
  46. 2026-07-21 16:18 UTCGHSA enrichment
  47. 2026-07-21 16:17 UTCGHSA enrichment
  48. 2026-07-21 16:16 UTCGHSA enrichment
  49. 2026-07-21 16:14 UTCGHSA enrichment
  50. 2026-07-21 16:12 UTCGHSA enrichment
  51. 2026-07-21 16:10 UTCGHSA enrichment
  52. 2026-07-21 16:10 UTCGHSA enrichment
  53. 2026-07-21 16:09 UTCGHSA enrichment
  54. 2026-07-21 16:08 UTCGHSA enrichment
  55. 2026-07-21 16:06 UTCGHSA enrichment
  56. 2026-07-21 16:05 UTCGHSA enrichment
  57. 2026-07-21 16:04 UTCGHSA enrichment
  58. 2026-07-21 16:03 UTCGHSA enrichment
  59. 2026-07-21 16:02 UTCGHSA enrichment
  60. 2026-07-21 15:58 UTCGHSA enrichment
  61. 2026-07-21 15:54 UTCGHSA enrichment
  62. 2026-07-21 15:52 UTCGHSA enrichment
  63. 2026-07-21 15:52 UTCGHSA enrichment
  64. 2026-07-21 15:48 UTCGHSA enrichment
  65. 2026-07-21 15:47 UTCGHSA enrichment
  66. 2026-07-21 15:46 UTCGHSA enrichment
  67. 2026-07-21 15:44 UTCGHSA enrichment
  68. 2026-07-21 15:41 UTCGHSA enrichment
  69. 2026-07-21 15:41 UTCGHSA enrichment
  70. 2026-07-21 15:39 UTCGHSA enrichment
  71. 2026-07-21 15:35 UTCGHSA enrichment
  72. 2026-07-21 15:32 UTCGHSA enrichment
  73. 2026-07-21 15:32 UTCGHSA enrichment
  74. 2026-07-21 15:31 UTCGHSA enrichment
  75. 2026-07-21 14:51 UTCNVD update

Frequently asked(5)

What is CVE-2026-16403?
CVE-2026-16403 is a medium vulnerability published on July 21, 2026. Spoofing issue in the Address Bar component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
When was CVE-2026-16403 disclosed?
CVE-2026-16403 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-2026-16403 actively exploited?
CVE-2026-16403 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-16403?
CVE-2026-16403 has a CVSS v3.1 base score of 6.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-16403?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16403, 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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