Vulnerability identifier: #VU15494

Vulnerability risk: Low

CVSSv3.1: 5.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-12395

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description
The vulnerability allows a remote attacker to bypass security restrictions on the target system.

The weakness exists due to an error in WebExtension. A remote attacker can trick the victim into visiting a specially crafted website, rewrite the Host request headers using the webRequest API and bypass domain restrictions through domain fronting. This would allow access to domains that share a host that are otherwise restricted.

Mitigation
Update to version 63.0.

Vulnerable software versions

Mozilla Firefox: 62.0 - 62.0.3

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2018-26/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.