Description
Mozilla developers reported memory safety bugs present in Firefox 92 and Firefox ESR 91.1. 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 affects Firefox < 93, Thunderbird < 91.2, and Firefox ESR < 91.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | unspecified – < 93 | 93 |
| Mozilla | Thunderbird | unspecified – < 91.2 | 91.2 |
| Mozilla | Firefox ESR | unspecified – < 91.2 | 91.2 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | mozjs78 | No fix yet | — |
| Ubuntu 22.04 LTS | thunderbird | 1:91.3.0+build2-0ubuntu1 | — |
| Ubuntu 20.04 LTS | firefox | 93.0+build1-0ubuntu0.20.04.1 | USN-5107-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 20.04 LTS | thunderbird | 1:91.5.0+build1-0ubuntu0.20.04.1 | USN-5248-1 |
| Ubuntu 18.04 LTS | firefox | 93.0+build1-0ubuntu0.18.04.1 | USN-5107-1 |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | thunderbird | 1:91.5.0+build1-0ubuntu0.18.04.1 | USN-5248-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | firefox | 91.2.0-4.el8_4 | RHSA-2021:3755 |
| RHEL 8 | thunderbird | 91.2.0-1.el8_4 | RHSA-2021:3838 |
| RHEL 7 | firefox | 91.2.0-4.el7_9 | RHSA-2021:3791 |
| RHEL 7 | thunderbird | 91.2.0-1.el7_9 | RHSA-2021:3841 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.2 EUS | firefox | 91.2.0-4.el8_2 | RHSA-2021:3756 |
| RHEL 8.2 EUS | thunderbird | 91.2.0-1.el8_2 | RHSA-2021:3839 |
| RHEL 8.1 EUS | firefox | 91.2.0-4.el8_1 | RHSA-2021:3757 |
| RHEL 8.1 EUS | thunderbird | 91.2.0-1.el8_1 | RHSA-2021:3840 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | firefox | 91.2.0-4.el8_4 | RLSA-2021:3755 |
| Rocky Linux 8 | thunderbird | 91.2.0-1.el8_4 | RLSA-2021:3838 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | MozillaFirefox | 91.2.0-8.54.1 | SUSE-SU-2021:3451-1 |
| SLES 15 SP3 | MozillaFirefox-branding-SLE | 91-9.5.1 | SUSE-SU-2021:3451-1 |
| SLES 15 SP3 | MozillaThunderbird | 91.4.0-8.45.2 | SUSE-SU-2021:4150-1 |
| SLES 15 SP2 | MozillaFirefox | 91.2.0-8.54.1 | SUSE-SU-2021:3451-1 |
| SLES 15 SP2 | MozillaFirefox-branding-SLE | 91-9.5.1 | SUSE-SU-2021:3451-1 |
| SLES 15 SP2 | MozillaThunderbird | 91.4.0-8.45.2 | SUSE-SU-2021:4150-1 |
| SLES 15 SP1 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLES 15 SP1 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SLES 15 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLES 15 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SLES 12 SP5 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
Show 17 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP4 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLES 12 SP3 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLES 12 SP2 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLES 11 SP4 | MozillaFirefox | 91.2.0-78.143.1 | SUSE-SU-2021:14826-1 |
| SLES 11 SP4 | MozillaFirefox-branding-SLED | 91-21.18.1 | SUSE-SU-2021:14826-1 |
| SLES for SAP 15 SP1 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLES for SAP 15 SP1 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SLES for SAP 15 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLES for SAP 15 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SLES for SAP 12 SP5 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLES for SAP 12 SP4 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SLE HPC 15 SP1 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLE HPC 15 SP1 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SLE HPC 15 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SLE HPC 15 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
| SUSE OpenStack Cloud Crowbar 9 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SUSE OpenStack Cloud Crowbar 8 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SUSE OpenStack Cloud 9 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SUSE OpenStack Cloud 8 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SUSE HPE Helion OpenStack 8 | MozillaFirefox | 91.2.0-112.74.1 | SUSE-SU-2021:3446-1 |
| SUSE Enterprise Storage 6 | MozillaFirefox | 91.2.0-3.155.2 | SUSE-SU-2021:3331-1 |
| SUSE Enterprise Storage 6 | MozillaFirefox-branding-SLE | 91-4.19.1 | SUSE-SU-2021:3331-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 93.0-1.1 | openSUSE-SU-2024:11570-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 91.2.0-1.1 | openSUSE-SU-2024:11571-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Leap 15.3 | MozillaFirefox | 91.2.0-8.54.1 | openSUSE-SU-2021:3451-1 |
| openSUSE Leap 15.3 | MozillaFirefox-branding-SLE | 91-9.5.1 | openSUSE-SU-2021:3451-1 |
| openSUSE Leap 15.3 | MozillaThunderbird | 91.4.0-8.45.2 | openSUSE-SU-2021:4150-1 |
| openSUSE Leap 15.3 | rust-cbindgen | 0.19.0-1.9.1 | openSUSE-SU-2021:3331-1 |
| openSUSE Leap 15.2 | MozillaFirefox | 91.2.0-lp152.2.67.1 | openSUSE-SU-2021:1367-1 |
| openSUSE Leap 15.2 | MozillaThunderbird | 91.4.0-lp152.2.52.1 | openSUSE-SU-2021:1635-1 |
| openSUSE Leap 15.2 | rust-cbindgen | 0.19.0-lp152.2.7.1 | openSUSE-SU-2021:1367-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | librewolf | 93.0-r0 | — |
| Alpine v3.23 | firefox +1 | 93.0-r0 | — |
| Alpine v3.23 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.23 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.22 | firefox +1 | 93.0-r0 | — |
| Alpine v3.22 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.22 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.21 | firefox +1 | 93.0-r0 | — |
| Alpine v3.21 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.21 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.20 | firefox | 93.0-r0 | — |
| Alpine v3.20 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.20 | thunderbird | 91.3.2-r0 | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | firefox | 93.0-r0 | — |
| Alpine v3.19 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.19 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.18 | firefox | 93.0-r0 | — |
| Alpine v3.18 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.18 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.17 | firefox | 93.0-r0 | — |
| Alpine v3.17 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.17 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.16 | firefox | 93.0-r0 | — |
| Alpine v3.16 | firefox-esr | 91.2.0-r0 | — |
| Alpine v3.16 | thunderbird | 91.3.2-r0 | — |
| Alpine v3.15 | firefox | 93.0-r0 | — |
| Alpine v3.15 | firefox-esr | 91.2.0-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | thunderbird | 91.6.0-1.amzn2.0.1 | ALAS2-2022-1818 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | firefox | 91.2.0-4.0.1.el8_4 | ELSA-2021-3755 |
| Oracle Linux 8 | thunderbird | 91.2.0-1.0.1.el8_4 | ELSA-2021-3838 |
| Oracle Linux 7 | firefox | 91.2.0-4.0.1.el7_9 | ELSA-2021-3791 |
| Oracle Linux 7 | thunderbird | 91.2.0-1.0.1.el7_9 | ELSA-2021-3841 |
Advisories 30
- RHSA-2021:3841 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2021:3791 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-5107-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-5248-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- RLSA-2021:3755 Important: firefox security update Rocky Linux Security Advisories · Feb 4, 2026
- RLSA-2021:3838 Important: thunderbird security update Rocky Linux Security Advisories · Feb 4, 2026
- openSUSE-SU-2021:3331-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:3446-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:4150-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:14826-1 Security update for MozillaFirefox, rust-cbindgen SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:4150-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1635-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:3331-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11570-1 MozillaFirefox-93.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:3451-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1367-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:3451-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:14572-1 firefox-esr-128.5.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11571-1 MozillaThunderbird-91.2.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- RHSA-2021:3840 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:3839 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:3838 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:3757 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:3755 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:3756 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- ALAS2-2022-1818 Important: thunderbird security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Aug 21, 2022
- ELSA-2021-3841 Important: thunderbird security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Oct 25, 2021
- ELSA-2021-3791 Important: firefox security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Oct 25, 2021
- ELSA-2021-3838 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 15, 2021
- ELSA-2021-3755 Important: firefox security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 11, 2021