#VU15494 Security restrictions bypass in Mozilla Firefox - CVE-2018-12395

Vulnerability identifier: #VU15494

Vulnerability risk: Low

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

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
https://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.