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: 0.2%CVSS: 5.4Exploit: None knownExposed services: Not assessed

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
5.4MEDIUMmedium confidence
EG Risk
24
EG Risk 24/100CISA 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
5th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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 19, 2026

Advisory Details (7)

Auto-updated Aug 18, 2026
Patch available.
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 / EcosystemFix (by version range) / 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_22026-09-08redhat
redhatfirefox-0:140.14.0-1.el7_92026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_62026-09-08redhat
redhatthunderbird-0:140.14.0-1.el9_42026-09-08redhat
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_42026-09-08redhat
redhatfirefox-0:140.14.0-1.el9_62026-09-08redhat
redhatfirefox-0:140.14.0-1.el8_82026-09-08redhat
redhatthunderbird-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.el10_02026-09-08redhat
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 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 21× 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 171 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

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 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 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-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?
A fix for CVE-2026-74963 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-74963 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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