CVE-2026-74960

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
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: 8.1Exploit: None knownExposed: 0

A fix is available — apply it.

Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS v3
8.1
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%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
6%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 24, 2026

Advisory Details (7)

Auto-updated Aug 21, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 153.1 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-80/
generic

Security Vulnerabilities fixed in Thunderbird 140.14 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-79/
generic

Security Vulnerabilities fixed in Thunderbird 154 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-78/
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 154 — Mozilla

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

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2049148

Vendor Advisories for CVE-2026-74960(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 / EcosystemFixed in / PatchReleasedSource
redhatthunderbird-0:140.14.0-1.el9_22026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_42026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_82026-09-09redhat
redhatfirefox-0:140.14.0-1.el9_22026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_62026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_102026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_42026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_82026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el10_22026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_82026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el10_02026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el10_02026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_62026-09-08redhat
redhatfirefox-0:140.14.0-1.el7_92026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_82026-08-24redhat
redhatfirefox-0:140.14.0-1.el8_102026-08-24redhat
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 rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (195 versions)140.14.0esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (224 versions)1:140.14.0esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (71 versions)140.14.0esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (80 versions)1:140.14.0esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (72 versions)140.14.0esr-2—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (81 versions)1:140.14.0esr-1—

Weakness Classification(2)

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 37× in last 7d / 157× 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 165 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-74960?
CVE-2026-74960 is a high vulnerability published on August 18, 2026. Site isolation issue in the WebExtensions component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
When was CVE-2026-74960 disclosed?
CVE-2026-74960 was first published in the National Vulnerability Database on August 18, 2026, with the most recent update on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74960 actively exploited?
CVE-2026-74960 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 94.0% of all scored CVEs.
What is the CVSS score of CVE-2026-74960?
CVE-2026-74960 has a CVSS v3.1 base score of 8.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74960?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74960, 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-2026-74960

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