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 7× in last 7d / 40× 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 226 total refreshes for this CVE.

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

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 76.5% 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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