CVE-2026-16399

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH 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 — 5 sources updated this week
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 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(high)
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
5.5%
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=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 32× in last 7d / 32× 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. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:05 UTCEG score recompute
  4. 2026-07-22 23:12 UTCEG score recompute
  5. 2026-07-22 23:12 UTCGHSA enrichment
  6. 2026-07-22 17:36 UTCEG score recompute▲ 7.50
  7. 2026-07-22 17:36 UTCGHSA enrichment
  8. 2026-07-22 17:35 UTCMITRE cvelistV5CVSS v3 → 7.5 · severity → HIGH
  9. 2026-07-22 14:08 UTCEPSS rescore
  10. 2026-07-21 19:10 UTCGHSA enrichment
  11. 2026-07-21 17:12 UTCGHSA enrichment
  12. 2026-07-21 17:03 UTCGHSA enrichment
  13. 2026-07-21 16:45 UTCGHSA enrichment
  14. 2026-07-21 16:40 UTCGHSA enrichment
  15. 2026-07-21 16:38 UTCGHSA enrichment
  16. 2026-07-21 16:36 UTCGHSA enrichment
  17. 2026-07-21 16:33 UTCGHSA enrichment
  18. 2026-07-21 16:25 UTCGHSA enrichment
  19. 2026-07-21 16:22 UTCGHSA enrichment
  20. 2026-07-21 16:19 UTCGHSA enrichment
  21. 2026-07-21 16:16 UTCGHSA enrichment
  22. 2026-07-21 16:12 UTCGHSA enrichment
  23. 2026-07-21 16:10 UTCGHSA enrichment
  24. 2026-07-21 16:06 UTCGHSA enrichment
  25. 2026-07-21 16:02 UTCGHSA enrichment
Show 7 more
  1. 2026-07-21 15:47 UTCGHSA enrichment
  2. 2026-07-21 15:32 UTCGHSA enrichment
  3. 2026-07-21 15:32 UTCGHSA enrichment
  4. 2026-07-21 15:31 UTCGHSA enrichment
  5. 2026-07-21 14:51 UTCNVD update
  6. 2026-07-21 12:48 UTCEG score recompute
  7. 2026-07-21 12:48 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

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 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-16399 actively exploited?
CVE-2026-16399 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 5.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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.

Dependency Blast Radius

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