Description
When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | — | 128.6 |
| Mozilla | Thunderbird | — | 128.6 |
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 | 128.6.0esr-1 | — |
| Debian 14 | thunderbird | 1:128.6.0esr-1 | — |
| Debian 13 | firefox-esr | 128.6.0esr-1 | — |
| Debian 13 | thunderbird | 1:128.6.0esr-1 | — |
| Debian 12 | firefox-esr | 128.6.0esr-1~deb12u1 | DSA-5839-1 |
| Debian 12 | thunderbird | 1:128.6.0esr-1~deb12u1 | DSA-5841-1 |
| Debian 11 | firefox-esr | 128.6.0esr-1~deb11u3 | DLA-4011-1 |
| Debian 11 | thunderbird | 1:128.6.0esr-1~deb11u1 | DLA-4012-1 |
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 | 134.0+build1-0ubuntu0.20.04.1 | USN-7191-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | firefox +1 | 128.6.0-1.el9_5 | RHSA-2025:0080 |
| RHEL 9 | thunderbird | 128.6.0-3.el9_5 | RHSA-2025:0147 |
| RHEL 8 | firefox | 128.6.0-1.el8_10 | RHSA-2025:0144 |
| RHEL 8 | thunderbird | 128.6.0-3.el8_10 | RHSA-2025:0281 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.4 EUS | firefox +1 | 128.6.0-1.el9_4 | RHSA-2025:0135 |
| RHEL 9.4 EUS | thunderbird | 128.6.0-3.el9_4 | RHSA-2025:0166 |
| RHEL 9.2 EUS | firefox +1 | 128.6.0-1.el9_2 | RHSA-2025:0138 |
| RHEL 9.2 EUS | thunderbird | 128.6.0-3.el9_2 | RHSA-2025:0167 |
| RHEL 9.0 E4S | firefox | 128.6.0-1.el9_0 | RHSA-2025:0162 |
| RHEL 9.0 E4S | thunderbird | 128.6.0-3.el9_0 | RHSA-2025:0165 |
| RHEL 8.8 EUS | firefox | 128.6.0-1.el8_8 | RHSA-2025:0137 |
| RHEL 8.8 EUS | thunderbird | 128.6.0-3.el8_8 | RHSA-2025:0284 |
| RHEL 8.6 TUS | firefox | 128.6.0-1.el8_6 | RHSA-2025:0136 |
| RHEL 8.6 TUS | thunderbird | 128.6.0-3.el8_6 | RHSA-2025:0275 |
| RHEL 8.6 E4S | firefox | 128.6.0-1.el8_6 | RHSA-2025:0136 |
| RHEL 8.6 E4S | thunderbird | 128.6.0-3.el8_6 | RHSA-2025:0275 |
| RHEL 8.6 AUS | firefox | 128.6.0-1.el8_6 | RHSA-2025:0136 |
| RHEL 8.6 AUS | thunderbird | 128.6.0-3.el8_6 | RHSA-2025:0275 |
| RHEL 8.4 TUS | firefox | 128.6.0-1.el8_4 | RHSA-2025:0134 |
| RHEL 8.4 TUS | thunderbird | 128.6.0-3.el8_4 | RHSA-2025:0287 |
| RHEL 8.4 E4S | firefox | 128.6.0-1.el8_4 | RHSA-2025:0134 |
| RHEL 8.4 E4S | thunderbird | 128.6.0-3.el8_4 | RHSA-2025:0287 |
| RHEL 8.4 AUS | firefox | 128.6.0-1.el8_4 | RHSA-2025:0134 |
| RHEL 8.4 AUS | thunderbird | 128.6.0-3.el8_4 | RHSA-2025:0287 |
| RHEL 8.2 AUS | firefox | 128.6.0-1.el8_2 | RHSA-2025:0133 |
| RHEL 8.2 AUS | thunderbird | 128.6.0-3.el8_2 | RHSA-2025:0286 |
| RHEL 7 ELS | firefox | 128.6.0-1.el7_9 | RHSA-2025:0132 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | firefox +1 | 128.6.0-1.el9_5 | ALSA-2025:0080 |
| AlmaLinux 8 | firefox | 128.6.0-1.el8_10 | ALSA-2025:0144 |
| AlmaLinux 8 | thunderbird | 128.6.0-3.el8_10.alma.1 | ALSA-2025:0281 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | firefox | 128.6.0-1.el8_10 | RLSA-2025:0144 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP6 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES 15 SP6 | MozillaThunderbird | 128.6.0-150200.8.197.1 | SUSE-SU-2025:0080-1 |
| SLES 15 SP5 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES 15 SP4 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES 15 SP3 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES 12 SP5 | MozillaFirefox | 128.6.0-112.243.1 | SUSE-SU-2025:0056-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 15 SP5 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES for SAP 15 SP4 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLES for SAP 15 SP3 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLE HPC 15 SP5 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLE HPC 15 SP4 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SLE HPC 15 SP3 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| SUSE Enterprise Storage 7.1 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 134.0-1.1 | openSUSE-SU-2025:14630-1 |
| openSUSE Tumbleweed | firefox-esr +1 | 128.6.0-1.1 | openSUSE-SU-2025:14648-1, openSUSE-SU-2025:14619-1 |
| openSUSE Tumbleweed | mozjs128 | 128.7.0-1.1 | openSUSE-SU-2025:14764-1 |
| openSUSE Leap 15.6 | MozillaFirefox | 128.6.0-150200.152.167.1 | SUSE-SU-2025:0059-1 |
| openSUSE Leap 15.6 | MozillaThunderbird | 128.6.0-150200.8.197.1 | SUSE-SU-2025:0080-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | firefox +1 | 128.6.0-1.0.1.el9_5 | ELSA-2025-0080 |
| Oracle Linux 8 | firefox | 128.6.0-1.0.1.el8_10 | ELSA-2025-0144 |
| Oracle Linux 7 | firefox | 128.6.0-1.0.1.el7_9 | ELSA-2025-0132 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | firefox | 134.0-r0 | — |
Advisories 40
- ALSA-2025:0281 Important: thunderbird security update AlmaLinux Security Advisories · Nov 6, 2026
- ALSA-2025:0080 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2025:0144 Important: firefox security update AlmaLinux Security Advisories · Oct 29, 2026
- USN-7191-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- RHSA-2025:0286 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0287 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0284 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0275 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0281 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0167 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0165 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0166 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0162 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0144 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0147 Red Hat Security Advisory: thunderbird security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0138 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0137 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0135 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0136 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0134 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0133 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0080 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- RHSA-2025:0132 Red Hat Security Advisory: firefox security update Red Hat Security Advisories (RHSA) · Apr 14, 2026
- DSA-5841-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-5839-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-4012-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-4011-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- RLSA-2025:0144 Important: firefox security update Rocky Linux Security Advisories · Feb 5, 2026
- SUSE-SU-2025:0056-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2025:14648-1 MozillaThunderbird-128.6.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2025:14764-1 libmozjs-128-0-128.7.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2025:0080-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2025:14619-1 firefox-esr-128.6.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2025:0059-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2025-0026 Mozilla Firefox, Firefox ESR und Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · Feb 2, 2026
- openSUSE-SU-2025:14630-1 MozillaFirefox-134.0-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- ELSA-2025-0132 Important: firefox security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jan 16, 2025
- NCSC-2025-0016 Kwetsbaarheden verholpen in Mozilla Firefox en Thunderbird NCSC-NL (Netherlands) · Jan 15, 2025
- ELSA-2025-0080 Important: firefox security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Jan 10, 2025
- ELSA-2025-0144 Important: firefox security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jan 10, 2025