CVE-2026-5731
Fixed in a distro release EPSS <1%CVSS 9.8
Memory safety bugs present in Firefox ESR 115.34.0, Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 115.34.1, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.
Products: Mozilla Firefox, Mozilla Thunderbird, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 7 Extended Lifecycle Support, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8.2 Advanced Update Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On, Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.6 Telecommunications Update Service, Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions, Red Hat Enterprise Linux 8.8 Telecommunications Update Service, Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.4 Extended Update Support, Red Hat Enterprise Linux 9.6 Extended Update Support, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux 10 | firefox | 140.9.1-1.el10_1 |
| AlmaLinux 10 | thunderbird | 140.9.1-1.el10_1.alma.1 |
| AlmaLinux 8 | firefox | 140.9.1-1.el8_10.alma.1 |
| AlmaLinux 8 | thunderbird | 140.9.1-1.el8_10.alma.1 |
| AlmaLinux 9 | firefox | 140.9.1-1.el9_7.alma.1 |
| AlmaLinux 9 | firefox-x11 | 140.9.1-1.el9_7.alma.1 |
| AlmaLinux 9 | thunderbird | 140.9.1-1.el9_7.alma.1 |
| Amazon Linux 2 | thunderbird | 140.9.1-1.amzn2.0.1 |
| Amazon Linux 2023 | firefox | 140.9.1-1.amzn2023.0.1 |
| Chainguard | firefox | 151.0.2-r0 |
| Chainguard | firefox-esr | 140.9.1-r0 |
| Debian 12 | firefox-esr | 140.9.1esr-1~deb12u1 |
| Debian 12 | thunderbird | 1:140.9.1esr-1~deb12u1 |
| Debian 13 | firefox-esr | 140.9.1esr-1~deb13u1 |
| Debian 13 | thunderbird | 1:140.9.1esr-1~deb13u1 |
| Debian 14 | firefox-esr | 140.9.1esr-1 |
| Debian 14 | thunderbird | 1:140.9.1esr-1 |
| Red Hat Enterprise Linux 10.1 | firefox | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 10.1 | firefox-debuginfo | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 10.1 | firefox-debugsource | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 10.1 | thunderbird | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 10.1 | thunderbird-debuginfo | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 10.1 | thunderbird-debugsource | 0:140.9.1-1.el10_1 |
| Red Hat Enterprise Linux 8 | firefox | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 8 | firefox-debuginfo | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 8 | firefox-debugsource | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 8 | thunderbird | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 8 | thunderbird-debuginfo | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 8 | thunderbird-debugsource | 0:140.9.1-1.el8_10 |
| Red Hat Enterprise Linux 9 | firefox | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | firefox-debuginfo | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | firefox-debugsource | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | firefox-x11 | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | thunderbird | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | thunderbird-debuginfo | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux 9 | thunderbird-debugsource | 0:140.9.1-1.el9_7 |
| Red Hat Enterprise Linux eus 10.0 | firefox | 0:140.9.1-1.el10_0 |
| Red Hat Enterprise Linux eus 10.0 | firefox-debuginfo | 0:140.9.1-1.el10_0 |
| Red Hat Enterprise Linux eus 10.0 | firefox-debugsource | 0:140.9.1-1.el10_0 |
| Red Hat Enterprise Linux eus 10.0 | thunderbird | 0:140.9.1-1.el10_0 |
| Red Hat Enterprise Linux eus 10.0 | thunderbird-debuginfo | 0:140.9.1-1.el10_0 |
| Red Hat Enterprise Linux eus 10.0 | thunderbird-debugsource | 0:140.9.1-1.el10_0 |
| Red Hat rhel aus 8.2 | firefox | 0:140.9.1-1.el8_2 |
| Red Hat rhel aus 8.2 | firefox-debuginfo | 0:140.9.1-1.el8_2 |
| Red Hat rhel aus 8.2 | firefox-debugsource | 0:140.9.1-1.el8_2 |
| Red Hat rhel aus 8.4 | firefox | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.4 | firefox-debuginfo | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.4 | firefox-debugsource | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.4 | thunderbird | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.4 | thunderbird-debuginfo | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.4 | thunderbird-debugsource | 0:140.9.1-1.el8_4 |
| Red Hat rhel aus 8.6 | firefox | 0:140.9.1-1.el8_6 |
| Red Hat rhel aus 8.6 | firefox-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel aus 8.6 | firefox-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel aus 8.6 | thunderbird | 0:140.9.1-1.el8_6 |
| Red Hat rhel aus 8.6 | thunderbird-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel aus 8.6 | thunderbird-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | firefox | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | firefox-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | firefox-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | thunderbird | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | thunderbird-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.6 | thunderbird-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel e4s 8.8 | firefox | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 8.8 | firefox-debuginfo | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 8.8 | firefox-debugsource | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 8.8 | thunderbird | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 8.8 | thunderbird-debuginfo | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 8.8 | thunderbird-debugsource | 0:140.9.1-1.el8_8 |
| Red Hat rhel e4s 9.0 | firefox | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.0 | firefox-debuginfo | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.0 | firefox-debugsource | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.0 | thunderbird | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.0 | thunderbird-debuginfo | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.0 | thunderbird-debugsource | 0:140.9.1-1.el9_0 |
| Red Hat rhel e4s 9.2 | firefox | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | firefox-debuginfo | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | firefox-debugsource | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | firefox-x11 | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | thunderbird | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | thunderbird-debuginfo | 0:140.9.1-1.el9_2 |
| Red Hat rhel e4s 9.2 | thunderbird-debugsource | 0:140.9.1-1.el9_2 |
| Red Hat rhel els 7 | firefox | 0:140.9.1-2.el7_9 |
| Red Hat rhel els 7 | firefox-debuginfo | 0:140.9.1-2.el7_9 |
| Red Hat rhel eus 9.4 | firefox | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | firefox-debuginfo | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | firefox-debugsource | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | firefox-x11 | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | thunderbird | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | thunderbird-debuginfo | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.4 | thunderbird-debugsource | 0:140.9.1-1.el9_4 |
| Red Hat rhel eus 9.6 | firefox | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | firefox-debuginfo | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | firefox-debugsource | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | firefox-x11 | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | thunderbird | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | thunderbird-debuginfo | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus 9.6 | thunderbird-debugsource | 0:140.9.1-1.el9_6 |
| Red Hat rhel eus long life 8.4 | firefox | 0:140.9.1-1.el8_4 |
| Red Hat rhel eus long life 8.4 | firefox-debuginfo | 0:140.9.1-1.el8_4 |
| Red Hat rhel eus long life 8.4 | firefox-debugsource | 0:140.9.1-1.el8_4 |
| Red Hat rhel eus long life 8.4 | thunderbird | 0:140.9.1-1.el8_4 |
| Red Hat rhel eus long life 8.4 | thunderbird-debuginfo | 0:140.9.1-1.el8_4 |
| Red Hat rhel eus long life 8.4 | thunderbird-debugsource | 0:140.9.1-1.el8_4 |
| Red Hat rhel tus 8.6 | firefox | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.6 | firefox-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.6 | firefox-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.6 | thunderbird | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.6 | thunderbird-debuginfo | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.6 | thunderbird-debugsource | 0:140.9.1-1.el8_6 |
| Red Hat rhel tus 8.8 | firefox | 0:140.9.1-1.el8_8 |
| Red Hat rhel tus 8.8 | firefox-debuginfo | 0:140.9.1-1.el8_8 |
| Red Hat rhel tus 8.8 | firefox-debugsource | 0:140.9.1-1.el8_8 |
| Red Hat rhel tus 8.8 | thunderbird | 0:140.9.1-1.el8_8 |
| Red Hat rhel tus 8.8 | thunderbird-debuginfo | 0:140.9.1-1.el8_8 |
| Red Hat rhel tus 8.8 | thunderbird-debugsource | 0:140.9.1-1.el8_8 |
| Rocky Linux 10 | firefox | 0:140.9.1-1.el10_1 |
| Rocky Linux 10 | thunderbird | 0:140.9.1-1.el10_1 |
| Rocky Linux 8 | firefox | 0:140.9.1-1.el8_10 |
| Rocky Linux 8 | thunderbird | 0:140.9.1-1.el8_10 |
| Rocky Linux 9 | firefox | 0:140.9.1-1.el9_7 |
| Rocky Linux 9 | thunderbird | 0:140.9.1-1.el9_7 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Module for Desktop Applications 15 SP7 | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Module for Package Hub 15 SP7 | MozillaThunderbird | 140.9.1-150200.8.266.1 |
| SUSE Linux Enterprise Server 12 SP5-LTSS | MozillaFirefox | 140.9.1-112.307.1 |
| SUSE Linux Enterprise Server 15 SP4-LTSS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server 15 SP5-LTSS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server 15 SP6-LTSS | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server 16.0 | MozillaFirefox | 140.9.1-160000.1.1 |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | MozillaFirefox | 140.9.1-112.307.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | MozillaFirefox | 140.9.1-150200.152.228.1 |
| SUSE Linux Enterprise Server for SAP applications 16.0 | MozillaFirefox | 140.9.1-160000.1.1 |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | MozillaThunderbird | 140.9.1-150200.8.266.1 |
| Ubuntu 18.04 LTS | mozjs38 | no fix |
| Ubuntu 18.04 LTS | mozjs52 | no fix |
| Ubuntu 20.04 LTS | mozjs52 | no fix |
| Ubuntu 20.04 LTS | mozjs68 | no fix |
| Ubuntu 22.04 LTS | mozjs102 | no fix |
| Ubuntu 22.04 LTS | mozjs78 | no fix |
| Ubuntu 22.04 LTS | mozjs91 | no fix |
| Ubuntu 22.04 LTS | thunderbird | no fix |
| Ubuntu 24.04 LTS | mozjs102 | no fix |
| Ubuntu 24.04 LTS | mozjs115 | no fix |
| Wolfi | firefox | 151.0.2-r0 |
| openSUSE Leap 16.0 | MozillaFirefox | 140.9.1-160000.1.1 |
| openSUSE Tumbleweed | MozillaFirefox | 149.0.2-1.1 |
| openSUSE Tumbleweed | MozillaThunderbird | 140.9.1-1.1 |
| openSUSE Tumbleweed | firefox-esr | 140.9.1-1.1 |