CVE-2026-12306

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 — 4 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

A fix is available — apply it.

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.

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
18%
KEV
Not listed

Published

June 16, 2026

Last Modified

June 18, 2026

Advisory Details (5)

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

Security Vulnerabilities fixed in Thunderbird 140.12 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-61/
generic

Security Vulnerabilities fixed in Thunderbird 152 — Mozilla

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

Security Vulnerabilities fixed in Firefox ESR 140.12 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-58/
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=2037323

Vendor Advisories for CVE-2026-12306(20)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(21)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatthunderbird-0:140.12.0-1.el9_22026-07-15redhat
redhatthunderbird-0:140.12.0-1.el8_42026-07-14redhat
redhatthunderbird-0:140.12.0-1.el8_82026-07-14redhat
redhatthunderbird-0:140.12.0-1.el8_62026-07-14redhat
redhatthunderbird-0:140.12.0-1.el9_62026-07-13redhat
redhatthunderbird-0:140.12.0-1.el9_42026-07-13redhat
redhatfirefox-0:140.12.0-1.el9_42026-07-13redhat
redhatfirefox-0:140.12.0-1.el7_92026-07-13redhat
redhatthunderbird-0:140.12.0-1.el10_02026-07-13redhat
redhatfirefox-0:140.12.0-1.el9_62026-07-09redhat
redhatfirefox-0:140.12.0-1.el8_62026-07-09redhat
redhatfirefox-0:140.12.0-1.el8_82026-07-07redhat
redhatfirefox-0:140.12.0-1.el8_42026-07-07redhat
redhatfirefox-0:140.12.0-1.el10_02026-07-07redhat
redhatfirefox-0:140.12.0-1.el9_22026-07-07redhat
redhatthunderbird-0:140.12.0-1.el8_102026-06-30redhat
redhatthunderbird-0:140.12.0-1.el10_22026-06-29redhat
redhatthunderbird-0:140.12.0-1.el9_82026-06-25redhat
redhatfirefox-0:140.12.0-1.el10_22026-06-22redhat
redhatfirefox-0:140.12.0-1.el8_102026-06-22redhat
redhatfirefox-0:140.12.0-1.el9_82026-06-22redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(8 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (279 versions)140.12.0esr-1~deb11u1—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (330 versions)1:140.12.0esr-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (186 versions)140.12.0esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (215 versions)1:140.12.0esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (62 versions)140.12.0esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (71 versions)1:140.12.0esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (63 versions)140.12.0esr-1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (72 versions)1:140.12.0esr-1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 43× 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 235 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 UTCVendor advisory
  4. 2026-09-14 03:32 UTCGHSA enrichment
  5. 2026-09-13 16:46 UTCEPSS rescore
  6. 2026-09-12 15:00 UTCEPSS rescore
  7. 2026-09-11 14:52 UTCEPSS rescore
  8. 2026-09-11 09:36 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-04 05:06 UTCEPSS rescore
  14. 2026-09-02 14:11 UTCEPSS rescore
  15. 2026-09-01 13:53 UTCEPSS rescore
  16. 2026-09-01 04:39 UTCEPSS rescore
  17. 2026-08-30 22:50 UTCEG score recompute
  18. 2026-08-30 22:50 UTCVendor advisory
  19. 2026-08-30 22:50 UTCGHSA enrichment
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 01:21 UTCEPSS rescore
  22. 2026-08-28 21:40 UTCEPSS rescore
  23. 2026-08-25 13:48 UTCEPSS rescore
  24. 2026-08-24 23:26 UTCEG score recompute
  25. 2026-08-24 23:26 UTCVendor advisory
Show 75 more
  1. 2026-08-24 23:26 UTCGHSA enrichment
  2. 2026-08-23 09:28 UTCEG score recompute
  3. 2026-08-23 09:28 UTCVendor advisory
  4. 2026-08-23 09:28 UTCGHSA enrichment
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-21 23:48 UTCEPSS rescore
  7. 2026-08-21 09:46 UTCEG score recompute
  8. 2026-08-21 09:46 UTCVendor advisory
  9. 2026-08-21 09:46 UTCGHSA enrichment
  10. 2026-08-20 22:55 UTCEPSS rescore
  11. 2026-08-20 11:26 UTCEG score recompute
  12. 2026-08-20 11:26 UTCVendor advisory
  13. 2026-08-20 11:26 UTCGHSA enrichment
  14. 2026-08-19 17:03 UTCEPSS rescore
  15. 2026-08-19 13:08 UTCEG score recompute
  16. 2026-08-19 13:08 UTCVendor advisory
  17. 2026-08-19 13:08 UTCGHSA enrichment
  18. 2026-08-18 13:48 UTCEPSS rescore
  19. 2026-08-17 07:53 UTCEG score recompute
  20. 2026-08-17 07:53 UTCVendor advisory
  21. 2026-08-17 07:53 UTCGHSA enrichment
  22. 2026-08-16 14:56 UTCEPSS rescore
  23. 2026-08-16 09:35 UTCEG score recompute
  24. 2026-08-16 09:35 UTCVendor advisory
  25. 2026-08-16 09:35 UTCGHSA enrichment
  26. 2026-08-16 02:14 UTCEPSS rescore
  27. 2026-08-15 11:18 UTCEG score recompute
  28. 2026-08-15 11:18 UTCVendor advisory
  29. 2026-08-15 11:18 UTCGHSA enrichment
  30. 2026-08-15 01:30 UTCEPSS rescore
  31. 2026-08-14 12:59 UTCEG score recompute
  32. 2026-08-14 12:59 UTCVendor advisory
  33. 2026-08-14 12:59 UTCGHSA enrichment
  34. 2026-08-13 22:00 UTCEPSS rescore
  35. 2026-08-13 14:40 UTCVendor advisory
  36. 2026-08-13 14:40 UTCGHSA enrichment
  37. 2026-08-12 16:13 UTCEG score recompute
  38. 2026-08-12 16:13 UTCVendor advisory
  39. 2026-08-12 16:13 UTCGHSA enrichment
  40. 2026-08-12 13:50 UTCEPSS rescore
  41. 2026-08-11 17:55 UTCEG score recompute
  42. 2026-08-11 17:55 UTCVendor advisory
  43. 2026-08-11 17:55 UTCGHSA enrichment
  44. 2026-08-11 13:42 UTCEPSS rescore
  45. 2026-08-10 23:59 UTCEPSS rescore
  46. 2026-08-10 19:25 UTCVendor advisory
  47. 2026-08-10 19:25 UTCGHSA enrichment
  48. 2026-08-09 18:15 UTCEG score recompute
  49. 2026-08-09 18:15 UTCVendor advisory
  50. 2026-08-09 18:15 UTCGHSA enrichment
  51. 2026-08-09 13:46 UTCEPSS rescore
  52. 2026-08-08 19:58 UTCEG score recompute
  53. 2026-08-08 19:58 UTCVendor advisory
  54. 2026-08-08 19:58 UTCGHSA enrichment
  55. 2026-08-08 16:37 UTCEPSS rescore
  56. 2026-08-07 21:40 UTCEG score recompute
  57. 2026-08-07 21:40 UTCVendor advisory
  58. 2026-08-07 21:40 UTCGHSA enrichment
  59. 2026-08-06 23:23 UTCEG score recompute
  60. 2026-08-06 23:23 UTCVendor advisory
  61. 2026-08-06 23:23 UTCGHSA enrichment
  62. 2026-08-06 13:46 UTCEPSS rescore
  63. 2026-08-06 00:10 UTCEG score recompute
  64. 2026-08-06 00:10 UTCVendor advisory
  65. 2026-08-06 00:10 UTCGHSA enrichment
  66. 2026-08-05 19:17 UTCEPSS rescore
  67. 2026-08-05 01:52 UTCEG score recompute
  68. 2026-08-05 01:52 UTCVendor advisory
  69. 2026-08-05 01:52 UTCGHSA enrichment
  70. 2026-08-04 15:09 UTCEPSS rescore
  71. 2026-08-04 10:38 UTCEPSS rescore
  72. 2026-08-04 03:18 UTCEG score recompute
  73. 2026-08-04 03:18 UTCVendor advisory
  74. 2026-08-04 03:18 UTCGHSA enrichment
  75. 2026-08-03 10:35 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-12306?
CVE-2026-12306 is a medium vulnerability published on June 16, 2026. Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
When was CVE-2026-12306 disclosed?
CVE-2026-12306 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-2026-12306 actively exploited?
CVE-2026-12306 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 82.0% of all scored CVEs.
What is the CVSS score of CVE-2026-12306?
CVE-2026-12306 has a CVSS v3.1 base score of 5.3 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-12306?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-12306, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-12306

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