CVE-2026-6786

HIGHPre-NVD 7.58.1▲
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-04-26. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 7.5; sources differ by 0.6.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

CVSS v3
7.5
EG Score
8.1(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: 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
Severity81% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
41%
KEV
Not listed

Published

April 26, 2026

Last Modified

July 15, 2026

Advisory Details (5)

Auto-updated May 4, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 140.10 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-34/
generic

Security Vulnerabilities fixed in Thunderbird 150 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-33/
generic

Security Vulnerabilities fixed in Firefox ESR 140.10 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-32/
generic

Security Vulnerabilities fixed in Firefox 150 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-30/
generic

Client Challenge

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2010727%2C2019004%2C2019224%2C2019547%2C2020378%2C2022381%2C2022608%2C2022785%2C2023120%2C2023128%2C2023140%2C2023279%2C2023836%2C2023882%2C2023925%2C2023950%2C2023959%2C2023965%2C2024243%2C2024245%2C2024247%2C2024253%2C2024346%2C2024357%2C2024416%2C2024420%2C2024429%2C2024432%2C2024455%2C2024466%2C2024468%2C2024476%2C2024664%2C2024666%2C2024669%2C2024670%2C2024671%2C2024761%2C2024918%2C2025292%2C2025332%2C2025348%2C2025384%2C2025395%2C2025458%2C2025461%2C2025463%2C2025481%2C2025483%2C2025485%2C2025494%2C2025506%2C2025511%2C2025513%2C2025520%2C2026277%2C2026282%2C2026288%2C2026289%2C2026311%2C2026312%2C2026869%2C2027152%2C2027161%2C2027238%2C2027261%2C2027269%2C2027274%2C2027280%2C2027281%2C2027300%2C2027302%2C2027331%2C2027339%2C2027340%2C2027738%2C2027975%2C2028000%2C2028011%2C2028289%2C2028525%2C2028728%2C2028887%2C2028888%2C2028896%2C2029063%2C2029064%2C2029290%2C2029291%2C2029294%2C2029300%2C2029304%2C2029316%2C2029317%2C2029401%2C2029415%2C2029430%2C2029457%2C2029727%2C2029735%2C2029743%2C2029752%2C2029754%2C2029776%2C2029809%2C2030324%2C2030370

Vendor Advisories for CVE-2026-6786(20)

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

Patch Availability(27)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatfirefox-0:140.10.0-1.el8_42026-05-20redhat
redhatfirefox-0:140.10.0-1.el9_42026-05-20redhat
redhatthunderbird-0:140.10.0-1.el8_62026-05-20redhat
redhatthunderbird-0:140.10.0-1.el9_02026-05-20redhat
redhatthunderbird-0:140.10.0-1.el9_62026-05-20redhat
redhatfirefox-0:140.10.0-1.el8_62026-05-20redhat
redhatthunderbird-0:140.10.0-1.el9_42026-05-20redhat
redhatthunderbird-0:140.10.0-1.el10_02026-05-20redhat
redhatthunderbird-0:140.10.0-1.el8_82026-05-20redhat
redhatthunderbird-0:140.10.0-1.el9_22026-05-20redhat
redhatthunderbird-0:140.10.0-1.el8_42026-05-20redhat
redhatfirefox-0:140.10.0-2.el7_92026-05-20redhat
redhatfirefox-0:140.10.0-1.el9_82026-05-19redhat
redhatfirefox-0:140.10.0-1.el10_22026-05-19redhat
redhatthunderbird-0:140.10.0-1.el10_22026-05-19redhat
redhatthunderbird-0:140.10.1-1.el9_82026-05-19redhat
redhatfirefox-0:140.10.0-1.el9_02026-05-14redhat
redhatfirefox-0:140.10.0-1.el10_02026-05-14redhat
redhatfirefox-0:140.10.0-1.el9_22026-05-14redhat
redhatfirefox-0:140.10.0-1.el9_62026-05-14redhat
redhatfirefox-0:140.10.0-1.el8_82026-05-14redhat
redhatthunderbird-0:140.10.0-1.el9_72026-05-11redhat
redhatthunderbird-0:140.10.0-1.el8_102026-05-04redhat
redhatthunderbird-0:140.10.0-1.el10_12026-04-30redhat
redhatfirefox-0:140.10.0-1.el10_12026-04-27redhat
redhatfirefox-0:140.10.0-1.el8_102026-04-27redhat
redhatfirefox-0:140.10.0-1.el9_72026-04-27redhat

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 (263 versions)140.10.0esr-1~deb11u1—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (314 versions)1:140.10.0esr-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (170 versions)140.10.0esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (199 versions)1:140.10.0esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (46 versions)140.10.0esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (55 versions)1:140.10.0esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (47 versions)140.10.0esr-1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (56 versions)1:140.10.0esr-1—

Weakness Classification(3)

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

Additional Vendor Advisories

(7)

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 5× in last 7d / 29× 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 240 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-6786?
CVE-2026-6786 is a high vulnerability published on April 26, 2026. Memory safety bugs present in Firefox ESR 140.9, Thunderbird ESR 140.9, Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in…
When was CVE-2026-6786 disclosed?
CVE-2026-6786 was first published in the National Vulnerability Database on April 26, 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-2026-6786 actively exploited?
CVE-2026-6786 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 58.7% of all scored CVEs.
What is the CVSS score of CVE-2026-6786?
CVE-2026-6786 has a CVSS v3.1 base score of 7.5 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1.
How do I remediate CVE-2026-6786?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6786, 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-2026-6786

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