Description
When "%2F" was present in a manifest URL, Firefox's AppCache behavior may have become confused and allowed a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory. This vulnerability affects Firefox < 78.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | unspecified – < 78 | 78 |
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 20.04 LTS | firefox | 78.0.1+build1-0ubuntu0.20.04.1 | USN-4408-1 |
| Ubuntu 20.04 LTS | mozjs52 +1 | No fix yet | — |
| Ubuntu 20.04 LTS | thunderbird | 1:78.7.1+build1-0ubuntu0.20.04.1 | — |
| Ubuntu 18.04 LTS | firefox | 78.0.1+build1-0ubuntu0.18.04.1 | USN-4408-1 |
| Ubuntu 18.04 LTS | mozjs38 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | thunderbird | 1:78.8.1+build1-0ubuntu0.18.04.1 | — |
| Ubuntu 16.04 LTS | firefox | 78.0.1+build1-0ubuntu0.16.04.1 | USN-4408-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP2 | MozillaFirefox | 78.0.1-3.94.2 | SUSE-SU-2020:1898-1 |
| SLES 15 SP2 | MozillaFirefox-branding-SLE | 78-4.14.1 | SUSE-SU-2020:1898-1 |
| SLES 15 SP1 | MozillaFirefox | 78.0.1-3.94.2 | SUSE-SU-2020:1898-1 |
| SLES 15 SP1 | MozillaFirefox-branding-SLE | 78-4.14.1 | SUSE-SU-2020:1898-1 |
| SLES 12 SP5 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP5 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP4 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP4 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP3 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP3 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP2 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES 12 SP2 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES 11 SP4 | MozillaFirefox | 78.0.1-78.80.2 | SUSE-SU-2020:14421-1 |
| SLES 11 SP4 | MozillaFirefox-branding-SLED | 78-21.12.1 | SUSE-SU-2020:14421-1 |
| SLES for SAP 12 SP5 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP5 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP4 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP4 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP3 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP2 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SLES for SAP 12 SP2 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud Crowbar 9 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud Crowbar 9 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud Crowbar 8 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud Crowbar 8 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 9 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 9 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 8 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 8 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 7 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE OpenStack Cloud 7 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE HPE Helion OpenStack 8 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE HPE Helion OpenStack 8 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
| SUSE Enterprise Storage 5 | MozillaFirefox | 78.0.1-112.3.1 | SUSE-SU-2020:1899-1 |
| SUSE Enterprise Storage 5 | MozillaFirefox-branding-SLE | 78-35.3.1 | SUSE-SU-2020:1899-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 92.0-1.2 | openSUSE-SU-2024:10600-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Leap 15.2 | MozillaFirefox | 78.0.1-lp152.2.5.1 | openSUSE-SU-2020:0983-1 |
| openSUSE Leap 15.1 | MozillaFirefox | 78.0.1-lp151.2.53.1 | openSUSE-SU-2020:1017-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | librewolf | 78.0-r0 | — |
| Alpine v3.23 | firefox +1 | 78.0-r0 | — |
| Alpine v3.22 | firefox +1 | 78.0-r0 | — |
| Alpine v3.21 | firefox +1 | 78.0-r0 | — |
| Alpine v3.20 | firefox | 78.0-r0 | — |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | firefox | 78.0-r0 | — |
| Alpine v3.18 | firefox | 78.0-r0 | — |
| Alpine v3.17 | firefox | 78.0-r0 | — |
| Alpine v3.16 | firefox | 78.0-r0 | — |
| Alpine v3.15 | firefox | 78.0-r0 | — |
| Alpine v3.14 | firefox | 78.0-r0 | — |
| Alpine v3.13 | firefox | 78.0-r0 | — |
| Alpine v3.12 | firefox | 78.0-r0 | — |
Advisories 9
- USN-4408-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- SUSE-SU-2020:1899-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2020:1017-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:14421-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10600-1 MozillaFirefox-92.0-1.2 on GA media 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
- openSUSE-SU-2020:0983-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2020:1898-1 Security update for MozillaFirefox SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-0457 Mozilla Firefox/Thunderbird: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 1, 2025
References
- https://www.mozilla.org/security/advisories/mfsa2020-24/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1586630
- openSUSE-SU-2020:0983 vendor-advisory
- openSUSE-SU-2020:1017 vendor-advisory
- GLSA-202007-10 vendor-advisory