CVE-2026-2777

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-02-24. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

Privilege escalation in the Messaging System component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
28.8%
KEV
Not listed

Published

February 24, 2026

Last Modified

July 15, 2026

Advisory Details (10)

Auto-updated Jul 16, 2026
🔬 Proof of concept available. Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support

https://access.redhat.com/errata/RHSA-2026:3491
redhat Patch Available

Affected: Red Hat Enterprise Linux 10.

https://access.redhat.com/errata/RHSA-2026:3361
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:3339
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2026:3338
generic

Security Vulnerabilities fixed in Thunderbird 140.8 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-17/
generic

Security Vulnerabilities fixed in Thunderbird 148 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-16/
generic

Security Vulnerabilities fixed in Firefox ESR 140.8 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-15/
generic

Security Vulnerabilities fixed in Firefox ESR 115.33 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-14/
generic

Security Vulnerabilities fixed in Firefox 148 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-13/
generic🟡 PoC Available

2015305 - (CVE-2026-2777) Compromised content process installs arbitrary WebExtensions or homepage hijacks (1-click) via AboutMessagePreviewParent IPC

https://bugzilla.mozilla.org/show_bug.cgi?id=2015305

Vendor Advisories for CVE-2026-2777(20)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(25)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatthunderbird-0:140.8.0-1.el8_22026-03-12redhat
redhatthunderbird-0:140.8.0-2.el10_02026-03-11redhat
redhatfirefox-0:140.8.0-2.el9_22026-03-10redhat
redhatthunderbird-0:140.8.0-1.el8_82026-03-09redhat
redhatthunderbird-0:140.8.0-1.el9_22026-03-09redhat
redhatthunderbird-0:140.8.0-1.el9_62026-03-09redhat
redhatthunderbird-0:140.8.0-1.el9_02026-03-09redhat
redhatfirefox-0:140.8.0-2.el7_92026-03-09redhat
redhatthunderbird-0:140.8.0-2.el8_42026-03-09redhat
redhatthunderbird-0:140.8.0-1.el8_62026-03-09redhat
redhatthunderbird-0:140.8.0-1.el9_42026-03-09redhat
redhatfirefox-0:140.8.0-2.el10_02026-03-09redhat
redhatfirefox-0:140.8.0-2.el8_42026-03-02redhat
redhatfirefox-0:140.8.0-2.el9_42026-03-02redhat
redhatthunderbird-0:140.8.0-2.el10_12026-03-02redhat
redhatthunderbird-0:140.8.0-1.el8_102026-03-02redhat
redhatfirefox-0:140.8.0-2.el8_22026-03-02redhat
redhatfirefox-0:140.8.0-2.el8_62026-03-02redhat
redhatthunderbird-0:140.8.0-1.el9_72026-03-02redhat
redhatfirefox-0:140.8.0-2.el9_02026-03-02redhat
redhatfirefox-0:140.8.0-2.el8_82026-03-02redhat
redhatfirefox-0:140.8.0-2.el9_62026-03-02redhat
redhatfirefox-0:140.8.0-2.el9_72026-02-25redhat
redhatfirefox-0:140.8.0-2.el8_102026-02-25redhat
redhatfirefox-0:140.8.0-2.el10_12026-02-25redhat

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

(5)

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 13× in last 7d / 45× 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 122 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-2777?
CVE-2026-2777 is a critical vulnerability published on February 24, 2026. Privilege escalation in the Messaging System component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
When was CVE-2026-2777 disclosed?
CVE-2026-2777 was first published in the National Vulnerability Database on February 24, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-2777 actively exploited?
CVE-2026-2777 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 28.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-2777?
CVE-2026-2777 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-2777?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-2777, 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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