CVE-2026-12300

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM 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
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 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(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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
Severity53% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
17%
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 8× in last 7d / 37× 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 175 total refreshes for this CVE.

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

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 0% probability of exploitation in the next 30 days, which ranks it in the top 83.2% of all scored CVEs.
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

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