CVE-2026-84134CWE-200information-disclosure

CVE-2026-84134

Critical · published September 1, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
46.4
In the wild
Unconfirmed
What it is

Other issue in the Profile Backup component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00570 · 46.4th percentile
Weakness
CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor
Published
2026-09-01T17:20Z
Affected products (4)
ProductVersionsFixed in
mozilla/firefox< 153.2.0153.2.0
mozilla/firefox≥ 154.0.0, < 155.0.0155.0.0
mozilla/thunderbird< 153.2.0153.2.0
mozilla/thunderbird≥ 154.0, < 155.0155.0
References (5)
https://bugzilla.mozilla.org/show_bug.cgi?id=2044882 · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-82/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-85/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-86/ · [email protected]https://www.mozilla.org/security/advisories/mfsa2026-88/ · [email protected]
EPSS history
Timeline
  • 03 SEP 03:32Z
    EPSS moved — → 0%
    epss
  • 01 SEP 12:19Z
    Other issue in the Profile Backup component
    cvelistv5