Description
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Thunderbird | unspecified – < 91.4.0 | 91.4.0 |
| Mozilla | Firefox ESR | unspecified – < 91.4.0 | 91.4.0 |
| Mozilla | Firefox | unspecified – < 95 | 95 |
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.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | firefox-esr | 91.4.0esr-1 | — |
| Debian 14 | thunderbird | 1:91.4.0-1 | — |
| Debian 13 | firefox-esr | 91.4.0esr-1 | — |
| Debian 13 | thunderbird | 1:91.4.0-1 | — |
| Debian 12 | firefox-esr | 91.4.0esr-1 | — |
| Debian 12 | thunderbird | 1:91.4.0-1 | — |
| Debian 11 | firefox-esr | 91.4.1esr-1~deb11u1 | DSA-5026-1 |
| Debian 11 | thunderbird | 1:91.4.1-1~deb11u1 | DSA-5034-1 |
| Debian 10 | thunderbird | 1:91.4.1-1~deb10u1 | DSA-5034-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 9 | firefox-esr | 91.4.1esr-1~deb9u1 | DLA-2863-1 |
| Debian 9 | thunderbird | 1:91.4.1-1~deb9u1 | DLA-2874-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | firefox | 95.0+build1-0ubuntu1 | — |
| Ubuntu 22.04 LTS | mozjs78 | No fix yet | — |
| Ubuntu 20.04 LTS | firefox | 95.0+build1-0ubuntu0.20.04.1 | USN-5186-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 20.04 LTS | thunderbird | 1:91.5.0+build1-0ubuntu0.20.04.1 | USN-5248-1 |
| Ubuntu 18.04 LTS | firefox | 95.0+build1-0ubuntu0.18.04.1 | USN-5186-1 |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | thunderbird | 1:91.5.0+build1-0ubuntu0.18.04.1 | USN-5248-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | firefox | 91.4.0-1.el8_5 | RHSA-2021:5013 |
| RHEL 8 | thunderbird | 91.4.0-2.el8_5 | RHSA-2021:5045 |
| RHEL 7 | firefox | 91.4.0-1.el7_9 | RHSA-2021:5014 |
| RHEL 7 | thunderbird | 91.4.0-3.el7_9 | RHSA-2021:5046 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8.4 EUS | firefox | 91.4.0-1.el8_4 | RHSA-2021:5015 |
| RHEL 8.4 EUS | thunderbird | 91.4.0-2.el8_4 | RHSA-2021:5048 |
| RHEL 8.2 EUS | firefox | 91.4.0-1.el8_2 | RHSA-2021:5016 |
| RHEL 8.2 EUS | thunderbird | 91.4.0-2.el8_2 | RHSA-2021:5047 |
| RHEL 8.1 E4S | firefox | 91.4.0-1.el8_1 | RHSA-2021:5017 |
| RHEL 8.1 E4S | thunderbird | 91.4.0-2.el8_1 | RHSA-2021:5055 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | firefox | 91.4.0-1.el8_5.alma | ALSA-2021:5013 |
| AlmaLinux 8 | thunderbird | 91.4.0-2.el8_5.alma | ALSA-2021:5045 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | firefox | 91.4.0-1.el8_5 | RLSA-2021:5013 |
| Rocky Linux 8 | thunderbird | 91.4.0-2.el8_5 | RLSA-2021:5045 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP3 | MozillaFirefox | 91.4.0-152.9.1 | SUSE-SU-2021:3993-1 |
| SLES 15 SP3 | MozillaThunderbird | 91.4.0-8.45.2 | SUSE-SU-2021:4150-1 |
| SLES 15 SP2 | MozillaFirefox | 91.4.0-152.9.1 | SUSE-SU-2021:3993-1 |
| SLES 15 SP2 | MozillaThunderbird | 91.4.0-8.45.2 | SUSE-SU-2021:4150-1 |
| SLES 15 SP1 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SLES 15 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SLES 12 SP5 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
Show 17 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP4 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLES 12 SP3 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLES 12 SP2 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLES 11 SP4 | MozillaFirefox | 91.4.0-78.154.1 | SUSE-SU-2021:14859-1 |
| SLES for SAP 15 SP1 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SLES for SAP 15 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SLES for SAP 12 SP5 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLES for SAP 12 SP4 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SLE HPC 15 SP1 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SLE HPC 15 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
| SUSE OpenStack Cloud Crowbar 9 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SUSE OpenStack Cloud Crowbar 8 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SUSE OpenStack Cloud 9 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SUSE OpenStack Cloud 8 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SUSE HPE Helion OpenStack 8 | MozillaFirefox | 91.4.0-112.83.1 | SUSE-SU-2021:4000-1 |
| SUSE Enterprise Storage 6 | MozillaFirefox | 91.4.0-150.9.1 | SUSE-SU-2021:3995-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 95.0-1.1 | openSUSE-SU-2024:11669-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 91.4.0-1.1 | openSUSE-SU-2024:11670-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Leap 15.3 | MozillaFirefox | 91.4.0-152.9.1 | openSUSE-SU-2021:3993-1 |
| openSUSE Leap 15.3 | MozillaThunderbird | 91.4.0-8.45.2 | openSUSE-SU-2021:4150-1 |
| openSUSE Leap 15.2 | MozillaFirefox | 91.4.0-lp152.2.74.1 | openSUSE-SU-2021:1575-1 |
| openSUSE Leap 15.2 | MozillaThunderbird | 91.4.0-lp152.2.52.1 | openSUSE-SU-2021:1635-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | librewolf | 95.0-r0 | — |
| Alpine v3.23 | firefox +1 | 95.0-r0 | — |
| Alpine v3.23 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.22 | firefox +1 | 95.0-r0 | — |
| Alpine v3.22 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.21 | firefox +1 | 95.0-r0 | — |
| Alpine v3.21 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.20 | firefox | 95.0-r0 | — |
| Alpine v3.20 | firefox-esr +1 | 91.4.0-r0 | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | firefox | 95.0-r0 | — |
| Alpine v3.19 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.18 | firefox | 95.0-r0 | — |
| Alpine v3.18 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.17 | firefox | 95.0-r0 | — |
| Alpine v3.17 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.16 | firefox | 95.0-r0 | — |
| Alpine v3.16 | firefox-esr +1 | 91.4.0-r0 | — |
| Alpine v3.15 | firefox-esr | 91.4.0-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | firefox | 91.4.0-1.0.1.el8_5 | ELSA-2021-5013 |
| Oracle Linux 8 | thunderbird | 91.4.0-2.0.1.el8_5 | ELSA-2021-5045 |
| Oracle Linux 7 | firefox | 91.4.0-1.0.1.el7_9 | ELSA-2021-5014 |
| Oracle Linux 7 | thunderbird | 91.4.0-3.0.1.el7_9 | ELSA-2021-5046 |
Advisories 39
- ALSA-2021:5045 Important: thunderbird security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2021:5013 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- WID-SEC-2022-0432 Xerox FreeFlow Print Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 11, 2026
- WID-SEC-2022-0302 Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen Ausführen von beliebigem Programmcode mit Administratorrechten BSI CERT-Bund (WID) · Oct 11, 2026
- RHSA-2021:5046 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2021:5014 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-5248-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-5186-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-5034-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-5026-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2863-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-2874-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2021:5013 Important: firefox security update Rocky Linux Security Advisories · Feb 4, 2026
- RLSA-2021:5045 Important: thunderbird security update Rocky Linux Security Advisories · Feb 4, 2026
- SUSE-SU-2021:4150-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:14859-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1575-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:3995-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:4150-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:3993-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:1635-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:11669-1 MozillaFirefox-95.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:4000-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2021:3993-1 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
- RHSA-2021:5048 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5055 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5047 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5045 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5017 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5015 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5016 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- RHSA-2021:5013 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- WID-SEC-2023-0839 Xerox FreeFlow Print Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 6, 2025
- openSUSE-SU-2024:11670-1 MozillaThunderbird-91.4.0-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- ELSA-2021-5045 Important: thunderbird security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Dec 10, 2021
- ELSA-2021-5046 Important: thunderbird security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Dec 10, 2021
- ELSA-2021-5013 Important: firefox security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Dec 9, 2021
- ELSA-2021-5014 Important: firefox security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Dec 8, 2021
References
- https://www.mozilla.org/security/advisories/mfsa2021-53/
- https://www.mozilla.org/security/advisories/mfsa2021-54/
- https://www.mozilla.org/security/advisories/mfsa2021-52/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1696685
- DSA-5026 vendor-advisory
- [debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update mailing-list
- DSA-5034 vendor-advisory
- [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update mailing-list
- GLSA-202202-03 vendor-advisory
- GLSA-202208-14 vendor-advisory