CVE-2026-84145: Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
Internally found bugs present in Firefox 154, Firefox ESR 153.1, Firefox ESR 140.14 and Firefox ESR 115.39. 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.
Other sources
Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. 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.
— Mozilla
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 155 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 140.15 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 115.40 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 153.2 - Upgrade
Upgrade
Firefoxto a version that resolves this vulnerability.Fixed in 155 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 115.40 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 140.15 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 153.2 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 155 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 140.15 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 153.2
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
- CVE-2026-84117
- CVE-2026-84118
- CVE-2026-84119
- CVE-2026-84120
- CVE-2026-84121
- CVE-2026-84122
- CVE-2026-84123
- CVE-2026-84124
- CVE-2026-84125
- CVE-2026-84126
- CVE-2026-84127
- CVE-2026-84128
- CVE-2026-84129
- CVE-2026-84130
- CVE-2026-84131
- CVE-2026-84132
- CVE-2026-84133
- CVE-2026-84134
- CVE-2026-84135
- CVE-2026-84136
- CVE-2026-84137
- CVE-2026-84138
- CVE-2026-84139
- CVE-2026-84140
- CVE-2026-84141
- CVE-2026-84142
- CVE-2026-84143
- CVE-2026-84144
- CVE-2026-84145
- CVE-2026-75874
- CVE-2026-16365
- CVE-2026-16371
- CVE-2026-74952
- CVE-2026-84639
- CVE-2026-84640
- CVE-2026-84641
- CVE-2026-84642
- CVE-2026-84637
Frequently Asked Questions
Which Firefox releases need to be updated?
Firefox 154, Firefox ESR 153.1, Firefox ESR 140.14, and Firefox ESR 115.39 contain the internally found bugs. Fixed releases are Firefox 155, Firefox ESR 153.2, Firefox ESR 140.15, and Firefox ESR 115.40.
Is exploitation known to have occurred?
The provided information says some bugs showed evidence of memory corruption or another security-relevant defect and could potentially have been exploited with sufficient effort. It does not state that exploitation has been observed.