Description
The developer page about:memory has a Measure function for exploring what object types the browser has allocated and their sizes. When this function was invoked we incorrectly called the sizeof function, instead of using the API method that checks for invalid pointers. This vulnerability affects Firefox < 86.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | < 86 | — |
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 20.04 LTS | firefox | 86.0+build3-0ubuntu0.20.04.1 | USN-4756-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | firefox | 86.0+build3-0ubuntu0.18.04.1 | USN-4756-1 |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
| Ubuntu 16.04 LTS | firefox | 86.0+build3-0ubuntu0.16.04.1 | USN-4756-1 |
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 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | librewolf | 87.0-r0 | — |
| Alpine v3.23 | firefox +1 | 87.0-r0 | — |
| Alpine v3.22 | firefox +1 | 87.0-r0 | — |
| Alpine v3.21 | firefox +1 | 87.0-r0 | — |
| Alpine v3.20 | firefox | 87.0-r0 | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | firefox | 87.0-r0 | — |
| Alpine v3.18 | firefox | 87.0-r0 | — |
| Alpine v3.17 | firefox | 87.0-r0 | — |
| Alpine v3.16 | firefox | 87.0-r0 | — |
| Alpine v3.15 | firefox | 87.0-r0 | — |
| Alpine v3.14 | firefox | 87.0-r0 | — |
| Alpine v3.13 | firefox | 87.0-r0 | — |
Advisories 3
- USN-4756-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- openSUSE-SU-2024:10600-1 MozillaFirefox-92.0-1.2 on GA media 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