CVE-2026-84144: Internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
Internally found bugs present in Firefox 154 and Firefox ESR 153.1. 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 and Thunderbird ESR 153.1. 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 153.2 - Upgrade
Upgrade
Mozilla Firefoxto a version that resolves this vulnerability.Fixed in 155 - Upgrade
Upgrade
Mozilla Firefox ESRto a version that resolves this vulnerability.Fixed in 153.2 - Upgrade
Upgrade
Mozilla Thunderbirdto a version that resolves this vulnerability.Fixed in 155 - Upgrade
Upgrade
Mozilla Thunderbird ESRto 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-2026-74952
- CVE-2026-84639
- CVE-2026-84640
- CVE-2026-84641
- CVE-2026-84642
- CVE-2026-84637
Frequently Asked Questions
Which installations are affected and which versions contain the fix?
Firefox 154 and Firefox ESR 153.1 are affected. The fixes are included in Firefox 155 and Firefox ESR 153.2.
Is exploitation confirmed?
The available information does not confirm exploitation. Some of the internally found bugs showed evidence of memory corruption or another security-relevant defect, and Mozilla presumes that some could have been exploitable with sufficient effort.