Vulnerability identifier: #VU18030

Vulnerability risk: High

CVSSv3.1: 8.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2019-9791

CWE-ID: CWE-843

Exploitation vector: Network

Exploit availability: Yes

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a type confusion error within the type inference system. The system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). A remote attacker can trick the victim to visit a specially crafted web page, trigger type confusion error and execute arbitrary code on the system with privileges of the current user.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 65.0.2

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2019-07/
http://bugzilla.mozilla.org/show_bug.cgi?id=1530958

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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. However, proof of concept for this vulnerability is available.