by Kastro
Paper/Archive/CVE-2026-84142

CVE-2026-84142

Mozilla Firefox — Internally found bugs fixed in Thunderbird 155

EPSS 0.6%CVSS 9.8
critical.is priorityof 100
39
CVSS 9.8 (ADP, NVD agree)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 46.7.467 × 209.3No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Internally found bugs present in Thunderbird 154. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155 and Thunderbird 155.

Affected

ProductAffectedFixed inSource
Firefoxsee advisory155CNA
Thunderbirdsee advisory155CNA

Scores by source

CISA ADP9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refbugzilla.mozilla.org/buglist.cgi?bug_id=2029421%2C2040889%2C2045313%2C2045435%2C2053578%2C2058621%2C2058626refbugzilla.mozilla.org/buglist.cgi?bug_id=2048796%2C2053150%2C2057356refmozilla.org/security/advisories/mfsa2026-82refmozilla.org/security/advisories/mfsa2026-86