Internally found bugs fixed in Thunderbird 155
Published Sep 1, 2026
9.8
CRITICALCVSS 3.1
EPSS 0.56%
Description
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 products
No data.
- < 155.0.0
- < 155.0
No data.
Red Hat Enterprise Linux 10
firefox
Not affected
Red Hat Enterprise Linux 10
rhel10/firefox-flatpak
Not affected
Red Hat Enterprise Linux 10
rhel10/thunderbird-flatpak
Not affected
Red Hat Enterprise Linux 10
thunderbird
Not affected
Red Hat Enterprise Linux 6
firefox
Not affected
Red Hat Enterprise Linux 6
thunderbird
Not affected
Red Hat Enterprise Linux 7
firefox
Not affected
Red Hat Enterprise Linux 7
thunderbird
Not affected
Red Hat Enterprise Linux 8
firefox
Not affected
Red Hat Enterprise Linux 8
thunderbird
Not affected
Red Hat Enterprise Linux 9
firefox
Not affected
Red Hat Enterprise Linux 9
thunderbird
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | firefox | Not affected | n/a |
| Red Hat Enterprise Linux 10 | rhel10/firefox-flatpak | Not affected | n/a |
| Red Hat Enterprise Linux 10 | rhel10/thunderbird-flatpak | Not affected | n/a |
| Red Hat Enterprise Linux 10 | thunderbird | Not affected | n/a |
| Red Hat Enterprise Linux 6 | firefox | Not affected | n/a |
| Red Hat Enterprise Linux 6 | thunderbird | Not affected | n/a |
| Red Hat Enterprise Linux 7 | firefox | Not affected | n/a |
| Red Hat Enterprise Linux 7 | thunderbird | Not affected | n/a |
| Red Hat Enterprise Linux 8 | firefox | Not affected | n/a |
| Red Hat Enterprise Linux 8 | thunderbird | Not affected | n/a |
| Red Hat Enterprise Linux 9 | firefox | Not affected | n/a |
| Red Hat Enterprise Linux 9 | thunderbird | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
References (11)
- https://access.redhat.com/security/cve/CVE-2026-84142 Vendor Advisory
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2029421%2C2040889%2C2045313%2C2045435%2C2053578%2C2058621%2C2058626 Issue Tracking
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048796%2C2053150%2C2057356 Issue Tracking
- https://bugzilla.redhat.com/show_bug.cgi?id=2526761 Issue Tracking
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-69090 Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-84142
- https://www.cve.org/CVERecord?id=CVE-2026-84142
- https://www.mozilla.org/security/advisories/mfsa2026-82/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-82/#CVE-2026-84142
- https://www.mozilla.org/security/advisories/mfsa2026-86/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-86/#CVE-2026-84142
Change history (0)
No recorded changes yet.