Description
Memory safety bugs present in Firefox 134 and Thunderbird 134. 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 135 and Thunderbird 135.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | — | 135 |
| Mozilla | Thunderbird | — | 135 |
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 24.04 LTS | mozjs102 +1 | No fix yet | — |
| Ubuntu 22.04 LTS | mozjs78 +2 | No fix yet | — |
| Ubuntu 22.04 LTS | thunderbird | 1:140.7.1+build1-0ubuntu0.22.04.1 | — |
| Ubuntu 20.04 LTS | firefox | 135.0+build2-0ubuntu0.20.04.1 | USN-7263-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 135.0-1.1 | openSUSE-SU-2025:14730-1 |
| openSUSE Tumbleweed | firefox-esr | 153.0-1.1 | openSUSE-SU-2026:11373-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | firefox | 135.0-r0 | — |
Advisories 5
- openSUSE-SU-2026:11373-1 firefox-esr-153.0-1.1 on GA media SUSE / openSUSE Security Updates · Jul 26, 2026
- USN-7263-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- openSUSE-SU-2025:14730-1 MozillaFirefox-135.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-0262 Mozilla Firefox und Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Feb 2, 2026
- NCSC-2025-0040 Kwetsbaarheden verholpen in Mozilla Firefox en Thunderbird NCSC-NL (Netherlands) · Feb 7, 2025