Description
Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | — | 153.2 |
| Mozilla | Thunderbird | — | 153.2 |
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 24.04 LTS | mozjs102 +1 | No fix yet | — |
| Ubuntu 22.04 LTS | mozjs78 +3 | No fix yet | — |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | MozillaThunderbird | 153.2.0-150400.13.3.1 | SUSE-SU-2026:4268-1 |
| SLES 15 SP7 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP7 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP6 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 12 SP5 | MozillaFirefox | 153.2.0-118.5.4 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | MozillaFirefox-branding-SLE | 153-41.3.8 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | mozilla-nspr | 4.39-19.39.1 | SUSE-SU-2026:4140-1 |
| SLES 12 SP5 | mozilla-nss | 3.125-58.147.1 | SUSE-SU-2026:4140-1 |
Show 10 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | SUSE-SU-2026:23784-1 |
| SLES for SAP 15 SP6 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP6 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLES for SAP 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLES 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | SUSE-SU-2026:23784-1 |
| SLE Micro 5.5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.3 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE Micro 5.3 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP5 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | MozillaFirefox | 153.2.0-150400.157.5.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | MozillaFirefox-branding-SLE | 153-150400.14.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | mozilla-nspr | 4.39-150400.12.3.1 | SUSE-SU-2026:4156-1 |
| SLE HPC 15 SP4 | mozilla-nss | 3.125-150400.3.74.1 | SUSE-SU-2026:4156-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 155.0-1.1 | openSUSE-SU-2026:11677-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 153.4.0-1.1 | openSUSE-SU-2026:12098-1 |
| openSUSE Tumbleweed | firefox-esr | 153.2.0-1.1 | openSUSE-SU-2026:11666-1 |
| openSUSE Leap 16.0 | MozillaFirefox | 153.2.0-160000.1.1 | openSUSE-SU-2026:21853-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | firefox +1 | 155.0.1-r0 | — |
Advisories 9
- WID-SEC-2026-3132 Mozilla Firefox und Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 8, 2026
- openSUSE-SU-2026:12098-1 MozillaThunderbird-153.4.0-1.1 on GA media SUSE / openSUSE Security Updates · Oct 11, 2026
- SUSE-SU-2026:4140-1 Security update for MozillaFirefox, mozilla-nspr, mozilla-nss, rust-cbindgen SUSE / openSUSE Security Updates · Sep 28, 2026
- SUSE-SU-2026:23784-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Sep 27, 2026
- SUSE-SU-2026:4268-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Sep 19, 2026
- openSUSE-SU-2026:21853-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Sep 17, 2026
- SUSE-SU-2026:4156-1 Security update for MozillaFirefox, MozillaFirefox-branding-SLE, mozilla-nspr, mozilla-nss, rust-cbindgen SUSE / openSUSE Security Updates · Sep 15, 2026
- openSUSE-SU-2026:11677-1 MozillaFirefox-155.0-1.1 on GA media SUSE / openSUSE Security Updates · Sep 5, 2026
- openSUSE-SU-2026:11666-1 firefox-esr-153.2.0-1.1 on GA media SUSE / openSUSE Security Updates · Sep 3, 2026
References
- Moderate Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
- High Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
- Low Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
- https://www.mozilla.org/security/advisories/mfsa2026-82/
- https://www.mozilla.org/security/advisories/mfsa2026-85/
- https://www.mozilla.org/security/advisories/mfsa2026-86/
- https://www.mozilla.org/security/advisories/mfsa2026-88/