CVE-2018-12395
By rewriting the Host: request headers using the webRequest API, a WebExtension can bypass domain restrictions through domain fronting.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.85%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
By rewriting the Host: request headers using the webRequest API, a WebExtension can bypass domain restrictions through domain fronting. This would allow access to domains that share a host that are otherwise restricted. This vulnerability affects Firefox ESR < 60.3 and Firefox < 63.
- CVSS 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 2.85% probability · 87th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Affected
- mozilla/firefox · mozilla/firefox esr · debian/debian linux · canonical/ubuntu linux · redhat/enterprise linux desktop · redhat/enterprise linux server · redhat/enterprise linux server eus · redhat/enterprise linux workstation
- Source
- security@mozilla.org
EPSS 2.9% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.securityfocus.com/bid/105718Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1041944Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:3005Third Party Advisory
- https://access.redhat.com/errata/RHSA-2018:3006Third Party Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1467523Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2018/11/msg00008.htmlMailing List, Third Party Advisory
- https://security.gentoo.org/glsa/201811-04Third Party Advisory
- https://usn.ubuntu.com/3801-1/Third Party Advisory
- https://www.debian.org/security/2018/dsa-4324Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2018-26/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2018-27/Vendor Advisory
- http://www.securityfocus.com/bid/105718Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1041944Third Party Advisory, VDB Entry
- https://access.redhat.com/errata/RHSA-2018:3005Third Party Advisory
- https://access.redhat.com/errata/RHSA-2018:3006Third Party Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1467523Issue Tracking, Permissions Required, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2018/11/msg00008.htmlMailing List, Third Party Advisory
- https://security.gentoo.org/glsa/201811-04Third Party Advisory
- https://usn.ubuntu.com/3801-1/Third Party Advisory
- https://www.debian.org/security/2018/dsa-4324Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2018-26/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2018-27/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.