CVE-2026-74956

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Same-origin policy bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 19, 2026

Advisory Details (5)

Auto-updated Sep 15, 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 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 154 — Mozilla

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

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2032406

Vendor Advisories for CVE-2026-74956(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 50× in last 7d / 210× 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 239 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-74956?
CVE-2026-74956 is a critical vulnerability published on August 18, 2026. Same-origin policy bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.
When was CVE-2026-74956 disclosed?
CVE-2026-74956 was first published in the National Vulnerability Database on August 18, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-74956 actively exploited?
CVE-2026-74956 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 79.0% of all scored CVEs.
What is the CVSS score of CVE-2026-74956?
CVE-2026-74956 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74956?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74956, 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

Explore the affected products and dependency analysis for CVE-2026-74956

Explore →

Is Your Infrastructure Affected by CVE-2026-74956?

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

Start Free Scan →Browse All CVEs