CVE-2026-8950

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

Score 9.3 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-19. NVD baseline CVSS 9.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.3Exploit: None knownExposed: 0

A fix is available — apply it.

Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: 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
Severity93% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

May 19, 2026

Last Modified

May 20, 2026

Advisory Details (5)

Auto-updated Aug 25, 2026
No patch confirmed yet.
generic

Security Vulnerabilities fixed in Thunderbird 140.11 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-51/
generic

Security Vulnerabilities fixed in Thunderbird 151 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-50/
generic

Security Vulnerabilities fixed in Firefox ESR 140.11 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-48/
generic

Security Vulnerabilities fixed in Firefox 151 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-46/
generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=1965430

Vendor Advisories for CVE-2026-8950(20)

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-0:140.11.0-1.el10_02026-06-22redhat
redhatfirefox-0:140.11.0-1.el8_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el7_92026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_82026-06-17redhat
redhatthunderbird-0:140.11.0-1.el8_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_42026-06-17redhat
redhatthunderbird-0:140.11.0-1.el9_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_22026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_42026-06-17redhat
redhatthunderbird-0:140.11.0-1.el10_02026-06-17redhat
redhatthunderbird-0:140.11.0-1.el9_42026-06-16redhat
redhatthunderbird-0:140.11.0-1.el8_42026-06-16redhat
redhatthunderbird-0:140.11.0-1.el8_82026-06-16redhat
redhatthunderbird-0:140.11.0-1.el9_22026-06-16redhat
redhatthunderbird-0:140.11.0-1.el8_102026-06-03redhat
redhatthunderbird-0:140.11.0-1.el10_22026-06-01redhat
redhatthunderbird-0:140.11.0-1.el9_82026-05-27redhat
redhatfirefox-0:140.11.0-1.el9_82026-05-27redhat
redhatfirefox-0:140.11.0-1.el8_102026-05-27redhat
redhatfirefox-0:140.11.0-1.el10_22026-05-27redhat

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

(8 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.1.0esr-1 ... 91.9.1esr-1~deb9u1 (275 versions)140.11.0esr-1~deb11u1—
thunderbird1:102.0.1-1 ... 1:91.9.0-1~deb9u1 (326 versions)1:140.11.0esr-1~deb11u1—
Debian:12(2)
PackageVulnerable rangeFixed inDependents
firefox-esr102.11.0esr-1 ... 140.9.1esr-1~deb13u1 (182 versions)140.11.0esr-1~deb12u1—
thunderbird1:102.11.0-1 ... 1:140.9.1esr-1~deb13u1 (211 versions)1:140.11.0esr-1~deb12u1—
Debian:13(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (58 versions)140.11.0esr-1~deb13u1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (67 versions)1:140.11.0esr-1~deb13u1—
Debian:14(2)
PackageVulnerable rangeFixed inDependents
firefox-esr128.13.0esr-1 ... 140.9.1esr-1~deb13u1 (59 versions)140.11.0esr-1—
thunderbird1:128.13.0esr-1 ... 1:140.9.1esr-1~deb13u1 (68 versions)1:140.11.0esr-1—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

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 15× in last 7d / 174× 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 450 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-8950?
CVE-2026-8950 is a critical vulnerability published on May 19, 2026. Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
When was CVE-2026-8950 disclosed?
CVE-2026-8950 was first published in the National Vulnerability Database on May 19, 2026, with the most recent update on May 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8950 actively exploited?
CVE-2026-8950 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 90.9% of all scored CVEs.
What is the CVSS score of CVE-2026-8950?
CVE-2026-8950 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-8950?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8950, 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-2026-8950

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