CVE-2019-9813

Mozilla: Ionmonkey type confusion with __proto__ mutations

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Severity

Critical

Red Hat Product Security

8.8

CVSS 3.0

Review impact separately from score.

Published · March 22, 2019

Updated · November 26, 2025

Description

Incorrect handling of proto mutations may lead to type confusion in IonMonkey JIT code and can be leveraged for arbitrary memory read and write. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.

Statement

In general, this flaw can be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or browser-like contexts.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.0 · 8.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE-843 · Access of Resource Using Incompatible Type ('Type Confusion')