CVE-2026-12300

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-06-16. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0

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

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

CVSS v3
5.3
EG Score
5.3(high)
EPSS
16.5%
KEV
Not listed

Published

June 16, 2026

Last Modified

June 18, 2026

Advisory Details (3)

Auto-updated Jun 16, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 152 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-60/
generic

Security Vulnerabilities fixed in Firefox 152 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-57/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=1704114

Vendor Advisories for CVE-2026-12300(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 22× in last 7d / 62× 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. 2026-07-07 00:12 UTCEG score recompute
  2. 2026-07-07 00:11 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 22:15 UTCEG score recompute
  6. 2026-07-05 22:15 UTCGHSA enrichment
  7. 2026-07-05 02:30 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 20:19 UTCEG score recompute
  10. 2026-07-04 20:19 UTCGHSA enrichment
  11. 2026-07-04 06:31 UTCEPSS rescore
  12. 2026-07-03 18:23 UTCEG score recompute
  13. 2026-07-03 18:23 UTCGHSA enrichment
  14. 2026-07-02 16:02 UTCEG score recompute
  15. 2026-07-02 16:02 UTCGHSA enrichment
  16. 2026-07-01 15:06 UTCEPSS rescore
  17. 2026-07-01 15:06 UTCEPSS rescore
  18. 2026-07-01 14:06 UTCEG score recompute
  19. 2026-07-01 14:06 UTCGHSA enrichment
  20. 2026-06-30 23:22 UTCEPSS rescore
  21. 2026-06-30 12:10 UTCEG score recompute
  22. 2026-06-30 12:10 UTCGHSA enrichment
  23. 2026-06-29 14:06 UTCEPSS rescore
  24. 2026-06-29 09:21 UTCEG score recompute
  25. 2026-06-29 09:21 UTCGHSA enrichment
Show 37 more
  1. 2026-06-28 14:07 UTCEPSS rescore
  2. 2026-06-28 07:24 UTCEG score recompute
  3. 2026-06-28 07:24 UTCGHSA enrichment
  4. 2026-06-28 04:56 UTCEPSS rescore
  5. 2026-06-28 04:56 UTCEPSS rescore
  6. 2026-06-27 05:29 UTCEG score recompute
  7. 2026-06-27 05:29 UTCGHSA enrichment
  8. 2026-06-27 03:08 UTCEPSS rescore
  9. 2026-06-26 03:34 UTCEG score recompute
  10. 2026-06-26 03:33 UTCGHSA enrichment
  11. 2026-06-25 13:49 UTCEPSS rescore
  12. 2026-06-25 01:37 UTCEG score recompute
  13. 2026-06-25 01:37 UTCGHSA enrichment
  14. 2026-06-24 14:05 UTCEPSS rescore
  15. 2026-06-23 23:42 UTCEG score recompute
  16. 2026-06-23 23:41 UTCGHSA enrichment
  17. 2026-06-23 21:32 UTCEPSS rescore
  18. 2026-06-22 21:45 UTCEG score recompute
  19. 2026-06-22 21:45 UTCGHSA enrichment
  20. 2026-06-22 14:25 UTCEPSS rescore
  21. 2026-06-22 14:25 UTCEPSS rescore
  22. 2026-06-21 19:22 UTCEG score recompute
  23. 2026-06-21 19:21 UTCGHSA enrichment
  24. 2026-06-21 14:56 UTCEPSS rescore
  25. 2026-06-21 14:56 UTCEPSS rescore
  26. 2026-06-21 01:59 UTCEPSS rescore
  27. 2026-06-21 01:59 UTCEPSS rescore
  28. 2026-06-20 17:25 UTCEG score recompute
  29. 2026-06-20 17:25 UTCGHSA enrichment
  30. 2026-06-19 19:25 UTCEPSS rescore
  31. 2026-06-19 15:27 UTCEG score recompute▲ 5.30
  32. 2026-06-19 15:27 UTCGHSA enrichment
  33. 2026-06-18 17:52 UTCEPSS rescore
  34. 2026-06-17 17:53 UTCEPSS rescore
  35. 2026-06-16 19:48 UTCNVD updateCVSS v3 → 5.3 · severity → MEDIUM
  36. 2026-06-16 13:49 UTCEG score recompute
  37. 2026-06-16 13:46 UTCNVD updatefirst tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-12300?
CVE-2026-12300 is a medium vulnerability published on June 16, 2026. Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.
When was CVE-2026-12300 disclosed?
CVE-2026-12300 was first published in the National Vulnerability Database on June 16, 2026, with the most recent update on June 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-12300 actively exploited?
CVE-2026-12300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 16.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-12300?
CVE-2026-12300 has a CVSS v3.1 base score of 5.3 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-12300?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-12300, 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-2026-12300

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