#VU18824 Type Confusion in Firefox ESR and Mozilla Firefox - CVE-2019-11707

Vulnerability identifier: #VU18824

Vulnerability risk: Critical

CVSSv4.0: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red]

CVE-ID: CVE-2019-11707

CWE-ID: CWE-843

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 execute arbitrary code on the target system.

The vulnerability exists due to a type confusion error when manipulating JavaScript objects due to issues in Array.pop. A remote attacker can create a specially crafted web page, trick the victim into visiting it, trigger a type confusion error and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note: this vulnerability is being actively exploited in the wild along with SB2019062002 (CVE-2019-11708).

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Firefox ESR: 60.0 - 60.7.0

Mozilla Firefox: 61.0 - 67.0.2

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2019-18/
https://twitter.com/5aelo/status/1141273394723414016
https://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.