#VU6335 Sendbox bypass in Mozilla Firefox and Firefox ESR - CVE-2017-5456

Vulnerability identifier: #VU6335

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2017-5456

CWE-ID: CWE-265

Exploitation vector: Network

Exploit availability: No

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to read files from local filesystem.

The vulnerability exists due to an error in sendbox implementation. A remote attacker can bypass file system access protections in the sandbox using the file system request constructor through an IPC message.

Successful exploitation of the vulnerability may allow an attacker to read arbitrary files from the vulnerable system.

Mitigation
Update to Firefox 53 or Firefox ESR 52.1.

Vulnerable software versions

Mozilla Firefox: 52 - 52.0.2

Firefox ESR: 52.0 - 52.0.2

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2017-10/
https://www.mozilla.org/en-US/security/advisories/mfsa2017-12/

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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.