Description
Mozilla Firefox before 36.0 does not properly recognize the equivalence of domain names with and without a trailing . (dot) character, which allows man-in-the-middle attackers to bypass the HPKP and HSTS protection mechanisms by constructing a URL with this character and leveraging access to an X.509 certificate for a domain with this character.
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 14.04 LTS | firefox | 36.0+build2-0ubuntu0.14.04.4 | USN-2505-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 50.1.0-1.1 | openSUSE-SU-2024:10071-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
Advisories 3
- USN-2505-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 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-2024:10071-1 MozillaFirefox-50.1.0-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1065909
- http://www.mozilla.org/security/announce/2015/mfsa2015-13.html
- 72752 vdb-entry
- GLSA-201504-01 vendor-advisory
- openSUSE-SU-2015:0404 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
- openSUSE-SU-2015:0570 vendor-advisory
- USN-2505-1 vendor-advisory