CVE-2026-74939

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
8.8EG
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: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
40
EG Risk 40/100CISA 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
Severity88% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
37th
KEV
Not listed

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

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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

August 21, 2026

Advisory Details (5)

Auto-updated Aug 18, 2026
Patch available.
generic

Security Vulnerabilities fixed in Firefox ESR 153.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-77/
generic

Security Vulnerabilities fixed in Firefox ESR 140.14 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-76/
generic

Security Vulnerabilities fixed in Firefox ESR 115.39 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-75/
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=2054416

Vendor Advisories for CVE-2026-74939(16)

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 / EcosystemFix (by version range) / PatchReleasedSource
redhatthunderbird-0:140.14.0-1.el8_82026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_42026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_62026-09-09redhat
redhatfirefox-0:140.14.0-1.el9_22026-09-09redhat
redhatthunderbird-0:140.14.0-1.el9_22026-09-09redhat
redhatthunderbird-0:140.14.0-1.el9_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_42026-09-08redhat
redhatthunderbird-0:140.14.0-1.el10_22026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_82026-09-08redhat
redhatfirefox-0:140.14.0-1.el7_92026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_62026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el10_02026-09-08redhat
redhatfirefox-0:140.14.0-1.el10_02026-09-08redhat
redhatthunderbird-0:140.14.0-1.el8_102026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_82026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_102026-08-24redhat
redhatfirefox-0:140.14.0-1.el9_82026-08-24redhat
redhatfirefox-0:140.14.0-1.el10_22026-08-24redhat

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 (195 versions)
  • every version up to 140.14.0esr-1~deb12u1: fixed in 140.14.0esr-1~deb12u1
—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (224 versions)
  • every version up to 1:140.14.0esr-1~deb12u1: fixed in 1:140.14.0esr-1~deb12u1
—
Debian:13(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (71 versions)
  • every version up to 140.14.0esr-1~deb13u1: fixed in 140.14.0esr-1~deb13u1
—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (80 versions)
  • every version up to 1:140.14.0esr-1~deb13u1: fixed in 1:140.14.0esr-1~deb13u1
—
Debian:14(2)
PackageVulnerable rangeFix by version rangeDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (72 versions)
  • every version up to 140.14.0esr-2: fixed in 140.14.0esr-2
—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (81 versions)
  • every version up to 1:140.14.0esr-1: fixed in 1:140.14.0esr-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(6)

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 31× in last 7d / 144× 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 241 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-74939?
CVE-2026-74939 is a high vulnerability published on August 18, 2026. Privilege escalation in the DOM: Navigation component. This vulnerability was fixed in Firefox 154, Firefox ESR 115.39, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
When was CVE-2026-74939 disclosed?
CVE-2026-74939 was first published on August 18, 2026, with the most recent update on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74939 actively exploited?
CVE-2026-74939 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-2026-74939?
CVE-2026-74939 has a CVSS v3.1 base score of 8.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74939?
A fix for CVE-2026-74939 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-74939 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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