CVE-2026-16389

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-07-21. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 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: 9.8Exploit: None knownExposed: 0

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

Incorrect boundary conditions, integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
35%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 24, 2026

Advisory Details (3)

Auto-updated Jul 25, 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=2043887

Vendor Advisories for CVE-2026-16389(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 35× in last 7d / 38× 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. 2026-07-28 17:03 UTCEG score recompute
  2. 2026-07-28 17:03 UTCGHSA enrichment
  3. 2026-07-28 11:41 UTCGHSA enrichment
  4. 2026-07-28 07:36 UTCGHSA enrichment
  5. 2026-07-28 03:33 UTCGHSA enrichment
  6. 2026-07-27 23:32 UTCGHSA enrichment
  7. 2026-07-27 19:15 UTCGHSA enrichment
  8. 2026-07-27 15:13 UTCEG score recompute
  9. 2026-07-27 15:13 UTCGHSA enrichment
  10. 2026-07-27 14:13 UTCEPSS rescore
  11. 2026-07-27 10:52 UTCGHSA enrichment
  12. 2026-07-27 06:52 UTCGHSA enrichment
  13. 2026-07-27 02:49 UTCGHSA enrichment
  14. 2026-07-26 22:46 UTCGHSA enrichment
  15. 2026-07-26 18:45 UTCEG score recompute
  16. 2026-07-26 18:44 UTCGHSA enrichment
  17. 2026-07-26 14:54 UTCEPSS rescore
  18. 2026-07-26 14:54 UTCEPSS rescore
  19. 2026-07-26 14:42 UTCGHSA enrichment
  20. 2026-07-26 10:42 UTCEG score recompute
  21. 2026-07-26 10:42 UTCGHSA enrichment
  22. 2026-07-26 04:22 UTCEG score recompute
  23. 2026-07-26 04:22 UTCGHSA enrichment
  24. 2026-07-25 14:17 UTCEPSS rescore
  25. 2026-07-25 14:17 UTCEPSS rescore
Show 13 more
  1. 2026-07-24 14:17 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 14:18 UTCEPSS rescore
  4. 2026-07-23 03:05 UTCEG score recompute
  5. 2026-07-22 23:13 UTCEG score recompute
  6. 2026-07-22 23:13 UTCGHSA enrichment
  7. 2026-07-22 17:37 UTCEG score recompute▲ 9.80
  8. 2026-07-22 17:36 UTCGHSA enrichment
  9. 2026-07-22 17:35 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  10. 2026-07-22 14:08 UTCEPSS rescore
  11. 2026-07-21 14:51 UTCNVD update
  12. 2026-07-21 12:48 UTCEG score recompute
  13. 2026-07-21 12:48 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-16389?
CVE-2026-16389 is a critical vulnerability published on July 21, 2026. Incorrect boundary conditions, integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 153 and Thunderbird 153.
When was CVE-2026-16389 disclosed?
CVE-2026-16389 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-2026-16389 actively exploited?
CVE-2026-16389 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 65.3% of all scored CVEs.
What is the CVSS score of CVE-2026-16389?
CVE-2026-16389 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-16389?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16389, 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

Explore the affected products and dependency analysis for CVE-2026-16389

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