CVE-2026-75874

CRITICALPre-NVD 10.010.0
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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 (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory

Also known asEUVD-2026-60674 (ENISA EUVD) · GHSA-xxrc-g5c2-523g (GitHub Security Advisories)Source: ENISA EUVD

10.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • 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 60/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity100% × 45%
Impact severity (EG Severity): CVSS 10.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
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
39th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (10.0): severity, escalated by confirmed exploitation. This CVE's 10.0 is its impact severity (EG Severity), not escalated.

EG Severity
10.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 18, 2026

Last Modified

September 1, 2026

Advisory Details (8)

Auto-updated Nov 6, 2026
Patch available.
Web page

Security Vulnerabilities fixed in Thunderbird 153.2 — Mozilla

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

Security Vulnerabilities fixed in Thunderbird 140.15 — Mozilla

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

Security Vulnerabilities fixed in Firefox ESR 153.2 — Mozilla

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

Security Vulnerabilities fixed in Firefox ESR 140.15 — Mozilla

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

Security Vulnerabilities fixed in Firefox ESR 115.40 — Mozilla

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

Security Vulnerabilities fixed in Thunderbird 154 — Mozilla

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

Security Vulnerabilities fixed in Firefox 154 — Mozilla

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

2039972 - (CVE-2026-75874) Firefox Content Process Sandbox Escape — macOS (Nimbus / Remote Settings Recipe Poison)

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

Patch Availability(21)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatthunderbird-0:140.16.0-1.el8_62026-10-13redhat
redhatthunderbird-0:140.16.0-1.el8_82026-10-13redhat
redhatthunderbird-0:140.16.0-1.el8_42026-10-13redhat
redhatthunderbird-0:140.15.0-1.el9_62026-10-12redhat
redhatthunderbird-0:140.15.0-1.el9_22026-10-08redhat
redhatthunderbird-0:140.15.0-1.el10_02026-10-08redhat
redhatthunderbird-0:140.15.0-1.el9_42026-10-08redhat
redhatfirefox-0:140.15.0-1.el10_02026-10-07redhat
redhatfirefox-0:140.15.0-1.el8_82026-10-06redhat
redhatfirefox-0:140.15.0-1.el9_22026-10-06redhat
redhatfirefox-0:140.15.0-1.el8_42026-10-06redhat
redhatfirefox-0:140.15.0-1.el8_62026-10-06redhat
redhatfirefox-0:140.15.0-1.el9_42026-10-06redhat
redhatfirefox-0:140.15.0-1.el9_62026-10-06redhat
redhatfirefox-0:140.15.0-1.el7_92026-10-06redhat
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.el10_22026-09-14redhat
redhatfirefox-0:140.15.0-1.el9_82026-09-14redhat

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 ... 1:153.1.0esr-1 (96 versions)
  • every version up to 1:153.2.0esr-1: fixed in 1:153.2.0esr-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 23× in last 7d / 94× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 532 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 432 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 02:09 UTCEchelonGraph re-scored
  2. 2026-11-13 02:09 UTCVendor advisory
  3. 2026-11-13 02:09 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  4. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  5. 2026-11-12 03:28 UTCEchelonGraph re-scored
  6. 2026-11-12 03:28 UTCVendor advisory
  7. 2026-11-12 03:28 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  8. 2026-11-11 16:40 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-11-11 04:49 UTCEchelonGraph re-scored
  10. 2026-11-11 04:49 UTCVendor advisory
  11. 2026-11-11 04:49 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  12. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-11-10 06:09 UTCEchelonGraph re-scored
  14. 2026-11-10 06:09 UTCVendor advisory
  15. 2026-11-10 06:09 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  16. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  17. 2026-11-09 07:29 UTCEchelonGraph re-scored
  18. 2026-11-09 07:29 UTCVendor advisory
  19. 2026-11-09 07:29 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  20. 2026-11-08 16:40 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  21. 2026-11-08 08:51 UTCEchelonGraph re-scored
  22. 2026-11-08 08:51 UTCVendor advisory
  23. 2026-11-08 08:51 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  24. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  25. 2026-11-07 10:11 UTCEchelonGraph re-scored
Show 75 more
  1. 2026-11-07 10:11 UTCVendor advisory
  2. 2026-11-07 10:11 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  3. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  4. 2026-11-06 11:29 UTCEchelonGraph re-scored
  5. 2026-11-06 11:29 UTCVendor advisory
  6. 2026-11-06 11:29 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  7. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  8. 2026-11-05 12:50 UTCEchelonGraph re-scored
  9. 2026-11-05 12:50 UTCVendor advisory
  10. 2026-11-05 12:50 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  11. 2026-11-04 16:36 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  12. 2026-11-04 14:11 UTCEchelonGraph re-scored
  13. 2026-11-04 14:11 UTCVendor advisory
  14. 2026-11-04 14:11 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  15. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  16. 2026-11-03 15:31 UTCVendor advisory
  17. 2026-11-03 15:31 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  18. 2026-11-02 16:51 UTCEchelonGraph re-scored
  19. 2026-11-02 16:51 UTCVendor advisory
  20. 2026-11-02 16:51 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  21. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  22. 2026-11-01 18:05 UTCEchelonGraph re-scored
  23. 2026-11-01 18:05 UTCVendor advisory
  24. 2026-11-01 18:05 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  25. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  26. 2026-10-31 19:26 UTCEchelonGraph re-scored
  27. 2026-10-31 19:26 UTCVendor advisory
  28. 2026-10-31 19:25 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  29. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  30. 2026-10-30 20:46 UTCEchelonGraph re-scored
  31. 2026-10-30 20:46 UTCVendor advisory
  32. 2026-10-30 20:46 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  33. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  34. 2026-10-29 22:08 UTCEchelonGraph re-scored
  35. 2026-10-29 22:08 UTCVendor advisory
  36. 2026-10-29 22:08 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  37. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  38. 2026-10-28 23:28 UTCEchelonGraph re-scored
  39. 2026-10-28 23:28 UTCVendor advisory
  40. 2026-10-28 23:28 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  41. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  42. 2026-10-28 00:47 UTCEchelonGraph re-scored
  43. 2026-10-28 00:47 UTCVendor advisory
  44. 2026-10-28 00:47 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  45. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  46. 2026-10-27 02:05 UTCEchelonGraph re-scored
  47. 2026-10-27 02:05 UTCVendor advisory
  48. 2026-10-27 02:05 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  49. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  50. 2026-10-25 23:24 UTCEchelonGraph re-scored
  51. 2026-10-25 23:24 UTCVendor advisory
  52. 2026-10-25 23:23 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  53. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  54. 2026-10-25 14:02 UTCEchelonGraph re-scored
  55. 2026-10-25 00:42 UTCEchelonGraph re-scored
  56. 2026-10-25 00:42 UTCVendor advisory
  57. 2026-10-25 00:42 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  58. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  59. 2026-10-24 02:03 UTCEchelonGraph re-scored
  60. 2026-10-24 02:03 UTCVendor advisory
  61. 2026-10-24 02:03 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  62. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  63. 2026-10-23 03:24 UTCEchelonGraph re-scored
  64. 2026-10-23 03:24 UTCVendor advisory
  65. 2026-10-23 03:23 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  66. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  67. 2026-10-22 04:42 UTCEchelonGraph re-scored
  68. 2026-10-22 04:42 UTCVendor advisory
  69. 2026-10-22 04:41 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  70. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  71. 2026-10-21 05:59 UTCEchelonGraph re-scored
  72. 2026-10-21 05:59 UTCVendor advisory
  73. 2026-10-21 05:58 UTCGHSA enrichmentGHSA-xxrc-g5c2-523g · GitHub severity CRITICAL · GitHub CVSS 10.0
  74. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  75. 2026-10-20 07:17 UTCEchelonGraph re-scored

Frequently asked(5)

What is CVE-2026-75874?
CVE-2026-75874 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-75874 published?
The CVE record for CVE-2026-75874 was published on August 18, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
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 (39th 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

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