Vulnerability identifier: #VU18860

Vulnerability risk: High

CVSSv3.1: 7.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2019-11708

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: Yes

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to bypass sandbox restrictions.

The vulnerability exists due to insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes. A remote attacker can create a specially crafted web page that can make the non-sandboxed parent process open web content chosen by a compromised child process.

An attacker can combine this behavior along with another vulnerability to execute arbitrary code on the system with privileges on the current user. 

Note, this vulnerability is being exploited in the wild along with SB2019061805 (CVE-2019-11707)

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Firefox ESR: 60.0 - 60.7.1

Mozilla Firefox: 61.0 - 67.0.3

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2019-19/
http://twitter.com/5aelo/status/1141273394723414016
http://twitter.com/SecurityGuyPhil/status/1141466335592869888

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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?

Yes. This vulnerability is being exploited in the wild.