CVE-2026-74963

MEDIUMPre-NVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

Score 5.4 from GitHub Security Advisory published 2026-08-18. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 4 sources updated this week
5.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.4Exploit: None knownExposed: 0

A fix is available — apply it.

Same-origin policy bypass in the Networking: Cookies 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
5.4
EG Score
5.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 19, 2026

Advisory Details (7)

Auto-updated Aug 18, 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=2050482

Vendor Advisories for CVE-2026-74963(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
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_42026-09-09redhat
redhatthunderbird-0:140.14.0-1.el8_82026-09-09redhat
redhatthunderbird-0:140.14.0-1.el9_22026-09-09redhat
redhatthunderbird-0:140.14.0-1.el10_02026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el10_22026-09-08redhat
redhatfirefox-0:140.14.0-1.el10_02026-09-08redhat
redhatfirefox-0:140.14.0-1.el7_92026-09-08redhat
redhatthunderbird-0:140.14.0-1.el8_102026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_82026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_42026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_62026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_82026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_102026-08-24redhat
redhatfirefox-0:140.14.0-1.el10_22026-08-24redhat
redhatfirefox-0:140.14.0-1.el9_82026-08-24redhat

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(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 24× in last 7d / 102× 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 118 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-74963?
CVE-2026-74963 is a medium vulnerability published on August 18, 2026. Same-origin policy bypass in the Networking: Cookies 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-2026-74963 disclosed?
CVE-2026-74963 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-2026-74963 actively exploited?
CVE-2026-74963 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 97.5% of all scored CVEs.
What is the CVSS score of CVE-2026-74963?
CVE-2026-74963 has a CVSS v3.1 base score of 5.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-74963?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-74963, 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-2026-74963

Explore →

Is Your Infrastructure Affected by CVE-2026-74963?

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

Start Free Scan →Browse All CVEs