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    CVE-2019-9792

    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.

    Published:Mar 20, 2019
    Last Modified:Nov 25, 2025
    EPS:Apr 26, 2019
    EPSS Score:0.19723
    CVSS Score:9.8

    Affected Products

    Vendor
    Mozilla
    Product
    Firefox
    Vendor
    Mozilla
    Product
    Thunderbird
    Vendor
    Redhat
    Product
    Enterprise Linux
    Vendor
    Redhat
    Product
    Enterprise Linux Eus
    Vendor
    Redhat
    Product
    Enterprise Linux Server Aus
    Vendor
    Redhat
    Product
    Enterprise Linux Server Tus

    Exploits

    http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlhttps://bugzilla.mozilla.org/show_bug.cgi?id=1532599http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlhttps://bugzilla.mozilla.org/show_bug.cgi?id=1532599https://www.exploit-db.com/exploits/46939

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-189 Black Box Reverse Engineering

    Related CVEs

    CVE-2026-84144 (CVSS 7.5) — Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. Some of these bugs showed evidence…
    CVE-2026-84143 (CVSS 9.8) — Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of th…
    CVE-2026-84142 (CVSS 9.8) — Internally found bugs present in Thunderbird 154. Some of these bugs showed evidence of memory corruption or a…
    CVE-2026-84141 (CVSS 9.8) — Integer overflow in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 155, Firefox ESR…
    CVE-2026-84140 (CVSS 9.8) — Site isolation issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ES…
    CVE-2026-84139 (CVSS 6.1) — Clickjacking issue in the DOM: Events component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.…
    CVE-2026-84138 (CVSS 6.5) — Denial-of-service in the PDF Viewer component. This vulnerability was fixed in Firefox 155 and Thunderbird 155…
    CVE-2026-84137 (CVSS 4.3) — Spoofing issue in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 155, Firefox ESR 153…
    CVE-2026-84136 (CVSS 6.1) — Other issue in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, …
    CVE-2026-84135 (CVSS 9.8) — Other issue in Firefox Focus for Android. This vulnerability was fixed in Firefox 155.…

    References

    http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.html
    https://access.redhat.com/errata/RHSA-2019:0966
    https://access.redhat.com/errata/RHSA-2019:1144
    https://bugzilla.mozilla.org/show_bug.cgi?id=1532599
    https://www.mozilla.org/security/advisories/mfsa2019-07/
    https://www.mozilla.org/security/advisories/mfsa2019-08/
    https://www.mozilla.org/security/advisories/mfsa2019-11/
    http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.html
    https://access.redhat.com/errata/RHSA-2019:0966
    https://access.redhat.com/errata/RHSA-2019:1144
    https://bugzilla.mozilla.org/show_bug.cgi?id=1532599
    https://www.mozilla.org/security/advisories/mfsa2019-07/
    https://www.mozilla.org/security/advisories/mfsa2019-08/
    https://www.mozilla.org/security/advisories/mfsa2019-11/

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High