#VU18062 Type Confusion in Firefox ESR and Mozilla Firefox - CVE-2019-9813

Vulnerability identifier: #VU18062

Vulnerability risk: High

CVSSv4.0: 7.3 [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:P/U:Amber]

CVE-ID: CVE-2019-9813

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 handling proto mutations in IonMonkey JIT code. 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.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Firefox ESR: 60.0 - 60.6.0

Mozilla Firefox: 61.0 - 66.0

---

External links
https://www.mozilla.org/en-US/security/advisories/mfsa2019-09/
https://www.mozilla.org/en-US/security/advisories/mfsa2019-10/
https://bugzilla.mozilla.org/show_bug.cgi?id=1538006

---

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.