CVE-2026-12299

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

Score 5.4 from GitHub Security Advisory published 2026-06-16. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

A fix is available — apply it.

JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

CVSS v3
5.4
EG Score
5.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

June 16, 2026

Last Modified

July 15, 2026

Advisory Details (4)

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

Security Vulnerabilities fixed in Firefox ESR 115.37 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-59/
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=2043139

Vendor Advisories for CVE-2026-12299(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_82026-07-14redhat
redhatthunderbird-0:140.12.0-1.el8_62026-07-14redhat
redhatthunderbird-0:140.12.0-1.el8_42026-07-14redhat
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_42026-07-13redhat
redhatthunderbird-0:140.12.0-1.el9_42026-07-13redhat
redhatthunderbird-0:140.12.0-1.el9_62026-07-13redhat
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_42026-07-07redhat
redhatfirefox-0:140.12.0-1.el10_02026-07-07redhat
redhatfirefox-0:140.12.0-1.el8_82026-07-07redhat
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(2)

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 20× in last 7d / 96× 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 202 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-12299?
CVE-2026-12299 is a medium vulnerability published on June 16, 2026. JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.
When was CVE-2026-12299 disclosed?
CVE-2026-12299 was first published in the National Vulnerability Database on June 16, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-12299 actively exploited?
CVE-2026-12299 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 77.4% of all scored CVEs.
What is the CVSS score of CVE-2026-12299?
CVE-2026-12299 has a CVSS v3.1 base score of 5.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-12299?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-12299, 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-2026-12299

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