CVE-2018-12395

critical
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
9.5

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.

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2018-12395

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2018-12395.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-201810-14

OS impact

OSVersionStatusFixed in
arch archfixed63.0-1
suse slesaffected
debian debiansidfixed63.0-1
debian debianbookwormfixed60.3.0esr-1
debian debianbullseyefixed60.3.0esr-1
debian debianforkyfixed60.3.0esr-1
debian debiantrixiefixed60.3.0esr-1

References

Verify integrity in audit chain (admin only). AS-IS.