Mozilla Firefox, Firefox ESR und Thunderbird: Mehrere Schwachstellen
WID-SEC-2026-0427 · first 17.02.2026 · updated 26.10.2026 · CVSS 8,8
What it is about
Firefox ist ein Open Source Web Browser. ESR ist die Variante mit verlängertem Support. Thunderbird ist ein Open Source E-Mail Client. Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Mozilla Firefox, Mozilla Firefox ESR und Mozilla Thunderbird ausnutzen, um falsche Informationen darzustellen oder nicht näher spezifizierte Auswirkungen zu verursachen
Under what conditions?
Over the network and without logging in. This is the most dangerous combination: attackers can scan reachable devices automatically.
What can happen in the worst case
An attacker could use the vulnerability to
- falsche Informationen darzustellen oder nicht näher spezifizierte Auswirkungen zu verursachen
Am I affected?
Affected according to the BSI:
- Debian Linux
- Amazon Linux 2
- Red Hat Enterprise Linux
- Ubuntu Linux
- SUSE Linux
- Oracle Linux
- SUSE openSUSE
- RESF Rocky Linux
- Mozilla Firefox ios <147.2.1
- Mozilla Firefox <147.0.4
- Mozilla Firefox ESR <115.32.1
- Mozilla Firefox ESR <140.7.1
and 3 more
The installed version is usually shown under “Help → About” or in the device’s admin interface.
What helps?
Update to at least:
- Mozilla Firefox ios 147.2.1
- Mozilla Firefox 147.0.4
- Mozilla Firefox ESR 115.32.1
- Mozilla Firefox ESR 140.7.1
- Mozilla Thunderbird 140.7.2
- Mozilla Thunderbird 147.0.2
- IBM QRadar SIEM 7.5.0 UP15 IF02
Is the vulnerability already being exploited?
None of the CVEs is in the CISA catalogue of exploited vulnerabilities. That does not mean there are no attacks, only that none are documented.
Information and sources
- Original BSI advisory (WID)
- Mozilla Security Advisory vom 2026-02-16 www.mozilla.org
- Mozilla Security Advisory vom 2026-02-16 www.mozilla.org
- Mozilla Security Advisory vom 2026-02-16 www.mozilla.org
- Debian Security Advisory DSA-6143 vom 2026-02-19 lists.debian.org
- Ubuntu Security Notice USN-8053-1 vom 2026-02-19 ubuntu.com
- openSUSE Security Update OPENSUSE-SU-2026:10218-1 vom 2026-02-19 lists.opensuse.org
- openSUSE Security Update OPENSUSE-SU-2026:10225-1 vom 2026-02-20 lists.opensuse.org
- Debian Security Advisory DLA-4489 vom 2026-02-22 lists.debian.org
- SUSE Security Update SUSE-SU-2026:0602-1 vom 2026-02-24 lists.suse.com
- SUSE Security Update SUSE-SU-2026:0611-1 vom 2026-02-25 lists.suse.com
- Red Hat Security Advisory RHSA-2026:3338 vom 2026-02-25 access.redhat.com
- Red Hat Security Advisory RHSA-2026:3361 vom 2026-02-25 access.redhat.com
- Oracle Linux Security Advisory ELSA-2026-3338 vom 2026-02-27 linux.oracle.com
- Oracle Linux Security Advisory ELSA-2026-3339 vom 2026-02-27 linux.oracle.com
- Oracle Linux Security Advisory ELSA-2026-3361 vom 2026-02-26 linux.oracle.com
- Rocky Linux Security Advisory RLSA-2026:3361 vom 2026-02-26 errata.build.resf.org
- Rocky Linux Security Advisory RLSA-2026:3339 vom 2026-02-26 errata.build.resf.org
- Rocky Linux Security Advisory RLSA-2026:3338 vom 2026-02-26 errata.build.resf.org
- SUSE Security Update SUSE-SU-2026:0692-1 vom 2026-02-28 lists.suse.com
- Rocky Linux Security Advisory RLSA-2026:3517 vom 2026-03-05 errata.build.resf.org
- Amazon Linux Security Advisory ALAS2-2026-3190 vom 2026-03-06 alas.aws.amazon.com
- Amazon Linux Security Advisory ALAS2FIREFOX-2026-053 vom 2026-03-06 alas.aws.amazon.com
- SUSE Security Update SUSE-SU-2026:20582-1 vom 2026-03-05 lists.suse.com
- Red Hat Security Advisory RHSA-2026:3967 vom 2026-03-09 access.redhat.com
- Red Hat Security Advisory RHSA-2026:3978 vom 2026-03-09 access.redhat.com
and 29 more sources in the original advisory
CVE: CVE-2026-2032, CVE-2026-2447
Source: BSI warning and information service (CERT-Bund); CISA. The assessment of the conditions is my reading of the BSI text; the external pages are in their original language.