CVE-2026-8956

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-19. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: None knownExposed: 0

A fix is available — apply it.

Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

May 19, 2026

Last Modified

May 20, 2026

Advisory Details (5)

Auto-updated Jul 26, 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=2032427

Vendor Advisories for CVE-2026-8956(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
redhatthunderbird-0:140.11.0-1.el8_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_42026-06-17redhat
redhatthunderbird-0:140.11.0-1.el10_02026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_22026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_62026-06-17redhat
redhatthunderbird-0:140.11.0-1.el9_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_82026-06-17redhat
redhatfirefox-0:140.11.0-1.el7_92026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_42026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_62026-06-17redhat
redhatthunderbird-0:140.11.0-1.el8_82026-06-16redhat
redhatthunderbird-0:140.11.0-1.el9_42026-06-16redhat
redhatthunderbird-0:140.11.0-1.el9_22026-06-16redhat
redhatthunderbird-0:140.11.0-1.el8_42026-06-16redhat
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.

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 9× in last 7d / 46× 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 299 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-8956?
CVE-2026-8956 is a critical vulnerability published on May 19, 2026. Integer overflow in the Networking: JAR component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
When was CVE-2026-8956 disclosed?
CVE-2026-8956 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-2026-8956 actively exploited?
CVE-2026-8956 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.6% of all scored CVEs.
What is the CVSS score of CVE-2026-8956?
CVE-2026-8956 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-8956?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8956, 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-2026-8956

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