CVE-2026-8958

HIGHNVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

Score 8.6 from GitHub Security Advisory (severity: HIGH) published 2026-05-19. NVD baseline CVSS 8.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: None knownExposed: 0

A fix is available — apply it.

Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

CVSS v3
8.6
EG Score
8.6(medium)
EG Risk
54(Track)
EG Risk 54/100SSVC: 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
Severity86% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
27%
KEV
Not listed

Published

May 19, 2026

Last Modified

May 20, 2026

Advisory Details (3)

Auto-updated May 19, 2026
No patch confirmed yet.
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=2034713

Vendor Advisories for CVE-2026-8958(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.el10_02026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_22026-06-17redhat
redhatfirefox-0:140.11.0-1.el9_42026-06-17redhat
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.el8_62026-06-17redhat
redhatfirefox-0:140.11.0-1.el7_92026-06-17redhat
redhatfirefox-0:140.11.0-1.el8_42026-06-17redhat
redhatthunderbird-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.el8_42026-06-16redhat
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_102026-06-03redhat
redhatthunderbird-0:140.11.0-1.el10_22026-06-01redhat
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
redhatthunderbird-0:140.11.0-1.el9_82026-05-27redhat

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(2)

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 10× in last 7d / 40× 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 151 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-8958?
CVE-2026-8958 is a high vulnerability published on May 19, 2026. Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
When was CVE-2026-8958 disclosed?
CVE-2026-8958 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-2026-8958 actively exploited?
CVE-2026-8958 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 73.1% of all scored CVEs.
What is the CVSS score of CVE-2026-8958?
CVE-2026-8958 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-8958?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8958, 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

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