CVE-2026-75874

CRITICALPre-NVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

Score 10.0 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 10.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — Patch released this week
10.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 10.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.

CVSS v3
10.0
EG Score
10.0CRITICALmedium confidence
EG Risk
60
EG Risk 60/100CISA SSVC

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
Severity100% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
37th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 18, 2026

Last Modified

September 1, 2026

Advisory Details (8)

Auto-updated Sep 29, 2026
Patch available.
generic

Security Vulnerabilities fixed in Thunderbird 153.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-88/
generic

Security Vulnerabilities fixed in Thunderbird 140.15 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-87/
generic

Security Vulnerabilities fixed in Firefox ESR 153.2 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-85/
generic

Security Vulnerabilities fixed in Firefox ESR 140.15 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-84/
generic

Security Vulnerabilities fixed in Firefox ESR 115.40 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-83/
generic

Security Vulnerabilities fixed in Thunderbird 154 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-78/
generic

Security Vulnerabilities fixed in Firefox 154 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-74/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2039972

Vendor Advisories for CVE-2026-75874(6)

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

Patch Availability(6)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatthunderbird-0:140.16.0-1.el8_102026-09-30redhat
redhatthunderbird-0:140.16.0-1.el10_22026-09-29redhat
redhatthunderbird-0:140.16.0-1.el9_82026-09-24redhat
redhatfirefox-0:140.15.0-1.el8_102026-09-17redhat
redhatfirefox-0:140.15.0-1.el9_82026-09-14redhat
redhatfirefox-0:140.15.0-1.el10_22026-09-14redhat

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

(6 across 3 ecosystems)
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (198 versions)
  • every version up to 140.15.0esr-1~deb12u1: fixed in 140.15.0esr-1~deb12u1
—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (227 versions)
  • every version up to 1:140.15.0esr-1~deb12u1: fixed in 1:140.15.0esr-1~deb12u1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (74 versions)
  • every version up to 140.15.0esr-1~deb13u1: fixed in 140.15.0esr-1~deb13u1
—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (83 versions)
  • every version up to 1:140.15.0esr-1~deb13u1: fixed in 1:140.15.0esr-1~deb13u1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (75 versions)
  • every version up to 140.15.0esr-1: fixed in 140.15.0esr-1
—
thunderbird1:128.13.0esr-1 ... 1:155.0.1-2 (99 versions)
  • every version on: no fix on record
—

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 59× in last 7d / 224× 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 370 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-75874?
CVE-2026-75874 is a critical vulnerability published on August 18, 2026. Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.
When was CVE-2026-75874 disclosed?
CVE-2026-75874 was first published on August 18, 2026, with the most recent update on September 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-75874 actively exploited?
CVE-2026-75874 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-75874?
CVE-2026-75874 has a CVSS v3.1 base score of 10.0 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-75874?
A fix for CVE-2026-75874 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-75874 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-75874

Explore →

Is Your Infrastructure Affected by CVE-2026-75874?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs