CVE-2019-9792

Mozilla: IonMonkey leaks JS_OPTIMIZED_OUT magic value to script

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Severity

Critical

Red Hat Product Security

9.8

CVSS 3.0

Review impact separately from score.

Published · March 20, 2019

Updated · June 27, 2026

Description

The IonMonkey just-in-time (JIT) compiler can leak an internal JS_OPTIMIZED_OUT magic value to the running script during a bailout. This magic value can then be used by JavaScript to achieve memory corruption, which results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Statement

In general, this flaw 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 · 9.8
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE-733 · Compiler Optimization Removal or Modification of Security-critical Code