Description
When in an endless loop, a website specifying a custom cursor using CSS could make it look like the user is interacting with the user interface, when they are not. This could lead to a perceived broken state, especially when interactions with existing browser dialogs and warnings do not work. This vulnerability affects Firefox ESR < 78.1, Firefox < 79, and Thunderbird < 78.1.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox ESR | unspecified – < 78.1 | 78.1 |
| Mozilla | Firefox | unspecified – < 79 | 79 |
| Mozilla | Thunderbird | unspecified – < 78.1 | 78.1 |
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 | firefox | 79.0+build1-0ubuntu0.20.04.1 | USN-4443-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 20.04 LTS | thunderbird | 1:78.7.1+build1-0ubuntu0.20.04.1 | — |
| Ubuntu 18.04 LTS | firefox | 79.0+build1-0ubuntu0.18.04.1 | USN-4443-1 |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | thunderbird | 1:78.8.1+build1-0ubuntu0.18.04.1 | — |
| Ubuntu 16.04 LTS | firefox | 79.0+build1-0ubuntu0.16.04.2 | USN-4443-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | firefox | 78.2.0-2.el8_2 | RHSA-2020:3557 |
| RHEL 7 | firefox | 78.3.0-1.el7_9 | RHSA-2020:4080 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.1 EUS | firefox | 78.2.0-3.el8_1 | RHSA-2020:3559 |
| RHEL 8.0 E4S | firefox | 78.2.0-3.el8_0 | RHSA-2020:3555 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | MozillaFirefox | 78.1.0-8.3.1 | SUSE-SU-2020:2147-1 |
| SLES 15 SP2 | MozillaFirefox-branding-SLE | 78-9.2.4 | SUSE-SU-2020:2147-1 |
| SLES 15 SP2 | pipewire | 0.3.6-3.3.2 | SUSE-SU-2020:2147-1 |
| SLES 15 SP1 | MozillaFirefox | 78.1.0-3.100.2 | SUSE-SU-2020:2118-1 |
| SLES 12 SP5 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES 12 SP4 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES 12 SP3 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES 11 SP4 | MozillaFirefox | 78.1.0-78.87.1 | SUSE-SU-2020:14456-1 |
| SLES for SAP 12 SP5 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES for SAP 12 SP4 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SLES for SAP 12 SP2 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE OpenStack Cloud Crowbar 9 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE OpenStack Cloud Crowbar 8 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE OpenStack Cloud 9 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE OpenStack Cloud 8 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE OpenStack Cloud 7 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE HPE Helion OpenStack 8 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
| SUSE Enterprise Storage 5 | MozillaFirefox | 78.1.0-112.8.1 | SUSE-SU-2020:2100-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 92.0-1.2 | openSUSE-SU-2024:10600-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Leap 15.2 | MozillaFirefox | 78.1.0-lp152.2.12.1 | openSUSE-SU-2020:1189-1, openSUSE-SU-2020:1155-1 |
| openSUSE Leap 15.2 | pipewire | 0.3.6-lp152.2.3.1 | openSUSE-SU-2020:1189-1 |
| openSUSE Leap 15.1 | MozillaFirefox | 78.1.0-lp151.2.61.1 | openSUSE-SU-2020:1147-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | librewolf | 79.0-r0 | — |
| Alpine v3.23 | firefox +1 | 79.0-r0 | — |
| Alpine v3.23 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.22 | firefox +1 | 79.0-r0 | — |
| Alpine v3.22 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.21 | firefox +1 | 79.0-r0 | — |
| Alpine v3.21 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.20 | firefox | 79.0-r0 | — |
| Alpine v3.20 | firefox-esr | 78.1.0-r0 | — |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | firefox | 79.0-r0 | — |
| Alpine v3.19 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.18 | firefox | 79.0-r0 | — |
| Alpine v3.18 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.17 | firefox | 79.0-r0 | — |
| Alpine v3.17 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.16 | firefox | 79.0-r0 | — |
| Alpine v3.16 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.15 | firefox | 79.0-r0 | — |
| Alpine v3.15 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.14 | firefox | 79.0-r0 | — |
| Alpine v3.14 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.13 | firefox | 79.0-r0 | — |
| Alpine v3.13 | firefox-esr | 78.1.0-r0 | — |
| Alpine v3.12 | firefox | 79.0-r0 | — |
| Alpine v3.12 | firefox-esr | 78.1.0-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | firefox | 78.2.0-2.0.1.el8_2 | ELSA-2020-3557 |
| Oracle Linux 7 | firefox | 78.3.0-1.0.1.el7_9 | ELSA-2020-4080 |
Advisories 16
- RHSA-2020:4080 Red Hat Security Advisory: firefox security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-4443-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- SUSE-SU-2020:14456-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1147-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1155-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:2147-1 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
- SUSE-SU-2020:2118-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1189-1 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
- SUSE-SU-2020:2100-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- RHSA-2020:3557 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jan 28, 2026
- RHSA-2020:3555 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jan 14, 2026
- RHSA-2020:3559 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jan 14, 2026
- ELSA-2020-4080 Important: firefox security and bug fix update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Oct 13, 2020
- ELSA-2020-3557 Important: firefox security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Aug 28, 2020