CVE-2019-9792

Name: CVE-2019-9792
Creator: NVD / NIST
Published: 2019-04-26T17:29:01.697+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 13.20%

Last modified Jun 17, 2026

CVE-2019-9792 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 13.20% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

13.20%

95.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 60.6.0
Mozilla	Firefox	< 66.0
Mozilla	Thunderbird	< 60.6.0
Redhat	Enterprise Linux	8.0
Redhat	Enterprise Linux Eus	8.1
Redhat	Enterprise Linux Eus	8.2
Redhat	Enterprise Linux Eus	8.4
Redhat	Enterprise Linux Server Aus	8.2
Redhat	Enterprise Linux Server Aus	8.4
Redhat	Enterprise Linux Server Tus	8.2
Redhat	Enterprise Linux Server Tus	8.4

References

http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlExploit, Third Party Advisory, VDB Entry
https://access.redhat.com/errata/RHSA-2019:0966Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1144Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1532599Exploit, Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory
http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlExploit, Third Party Advisory, VDB Entry
https://access.redhat.com/errata/RHSA-2019:0966Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1144Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1532599Exploit, Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory

Timeline

Published: Apr 26, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-9792?

How severe is CVE-2019-9792?

CVE-2019-9792 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 13.20% probability of exploitation in the next 30 days.

How do I fix CVE-2019-9792?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-9792?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST