Description
If hyperthreading is not disabled, a timing attack vulnerability exists, similar to previous Spectre attacks. Apple has shipped macOS 10.14.5 with an option to disable hyperthreading in applications running untrusted code in a thread through a new sysctl. Firefox now makes use of it on the main thread and any worker threads. *Note: users need to update to macOS 10.14.5 in order to take advantage of this change.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | unspecified – < 60.7 | 60.7 |
| Mozilla | Firefox | unspecified – < 67 | 67 |
| Mozilla | Firefox ESR | unspecified – < 60.7 | 60.7 |
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 20.04 LTS | mozjs52 | No fix yet | — |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP1 | MozillaFirefox | 60.7.0-3.40.6 | SUSE-SU-2019:1405-1 |
| SLES 15 SP1 | MozillaThunderbird | 60.7.0-3.33.2 | SUSE-SU-2019:1458-1 |
| SLES 15 | MozillaFirefox | 60.7.0-3.40.6 | SUSE-SU-2019:1405-1 |
| SLES 15 | MozillaThunderbird | 60.7.0-3.33.2 | SUSE-SU-2019:1458-1 |
| SLES 12 SP4 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES 12 SP3 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES 12 SP2 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES 12 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES for SAP 12 SP4 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES for SAP 12 SP2 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SLES for SAP 12 SP1 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SUSE Package Hub 12 | MozillaThunderbird | 60.7.2-85.1 | openSUSE-SU-2019:1664-1 |
| SUSE OpenStack Cloud 7 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
| SUSE Enterprise Storage 4 | MozillaFirefox | 60.7.0-109.72.1 | SUSE-SU-2019:1388-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 92.0-1.2 | openSUSE-SU-2024:10600-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 91.1.1-1.1 | openSUSE-SU-2024:10601-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Leap 15.0 | MozillaFirefox | 60.7.0-lp150.3.54.5 | openSUSE-SU-2019:1534-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.23 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.22 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.21 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.20 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.19 | firefox-esr | 60.7.0-r0 | — |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.18 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.17 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.16 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.15 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.14 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.13 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.12 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.11 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.10 | firefox-esr | 60.7.0-r0 | — |
| Alpine v3.9 | firefox-esr | 60.7.0-r0 | — |
Advisories 8
- SUSE-SU-2019:1458-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:1534-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10600-1 MozillaFirefox-92.0-1.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:1664-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1388-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1405-1 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-2024:10601-1 MozillaThunderbird-91.1.1-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025