#VU6333 Sendbox bypass in Mozilla Firefox and Firefox ESR - CVE-2017-5454

Vulnerability identifier: #VU6333

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-2017-5454

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 use the file picker to access different files than those selected in the file picker through the use of relative paths.

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.