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Fencer Intel
critical 9.8

CVE-2019-9792 in the critical feed json

The IonMonkey just-in-time (JIT) compiler can leak an internal JS_OPTIMIZED_OUT magic value to the running script during a bailout.

published 2019-04-26 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-19154

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
13.3%
EPSS 13.3% chance of exploitation in 30 days, percentile 96%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • Mozilla Thunderbird 60.6
  • Mozilla Firefox ESR 60.6
  • Mozilla Firefox 66
  • firefox-esr Debian 14, Debian 13, Debian 12 60.6.0esr-1
  • thunderbird Debian 14, Debian 13, Debian 12 1:60.6.1-1

debian advisories DEBIAN-CVE-2019-9792

  • firefox Ubuntu 14.04 LTS 66.0.1+build1-0ubuntu0.14.04.1
  • firefox Ubuntu 16.04 LTS 66.0+build3-0ubuntu0.16.04.2
  • firefox Ubuntu 18.04 LTS 66.0+build3-0ubuntu0.18.04.1
  • thunderbird Ubuntu 14.04 LTS 1:60.6.1+build2-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:60.6.1+build2-0ubuntu0.16.04.1
  • thunderbird Ubuntu 18.04 LTS 1:60.6.1+build2-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2019-9792

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • thunderbird RHEL 8 60.6.1-1.el8
  • thunderbird RHEL 7 60.6.1-1.el7_6
  • firefox RHEL 8 60.6.1-1.el8
  • thunderbird RHEL 6 60.6.1-1.el6_10
  • firefox RHEL 6 60.6.0-3.el6_10
  • firefox RHEL 7 60.6.0-3.el7_6

red hat advisories RHSA-2019:1144RHSA-2019:0681RHSA-2019:0966RHSA-2019:0680RHSA-2019:0623RHSA-2019:0622

  • MozillaFirefox SLE Module for Desktop Applications 15 60.6.1-3.29.3
  • MozillaThunderbird SLE Workstation Extension 15 60.6.1-3.28.1
  • MozillaFirefox SLES for SAP 12 SP4, SLES for SAP 12 SP3, SLES for SAP 12 SP2 +13 more 60.6.1esr-109.63.2

suse advisories SUSE-SU-2019:0871-1SUSE-SU-2019:0853-1SUSE-SU-2019:0852-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaThunderbird openSUSE Leap 15.0 60.6.1-lp150.3.37.1
  • MozillaThunderbird Package Hub 12 60.6.1-82.1
  • MozillaFirefox openSUSE Leap 15.0 60.6.1-lp150.3.45.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2019:1162-1openSUSE-SU-2019:1126-1openSUSE-SU-2019:1077-1

  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +12 more 60.6.1-r0

alpine advisories ALPINE-CVE-2019-9792

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox Arch Linux 66.0-1

arch linux advisories AVG-925

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-9792 updated cvss 9.8

Mozilla: IonMonkey leaks JS_OPTIMIZED_OUT magic value to script

  • Red Hat Enterprise Linux AppStream (v. 8) firefox 60.6.1-1.el8, thunderbird 60.6.1-1.el8
    fixed: vendor fix RHSA-2019:0966
  • Red Hat Enterprise Linux Client (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6 Red Hat Enterprise Linux Client Optional (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Desktop (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0681
  • Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 60.6.0-3.el6_10 Red Hat Enterprise Linux Server (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Server (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Server Optional (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10
    fixed: vendor fix RHSA-2019:0623
show 5 more
  • Red Hat Enterprise Linux Server Optional (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Workstation (v. 6) firefox 60.6.0-3.el6_10, thunderbird 60.6.1-1.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Workstation (v. 7) firefox 60.6.0-3.el7_6, thunderbird 60.6.1-1.el7_6
    fixed: vendor fix RHSA-2019:0622
  • Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 60.6.0-3.el6_10
    fixed: vendor fix RHSA-2019:0623
  • Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 60.6.0-3.el7_6
    fixed: vendor fix RHSA-2019:0622

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. Published
  2. First public exploit (EDB-46939)

Exploit prediction

13.30% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-46939 Spidermonkey - IonMonkey Leaks JS_OPTIMIZED_OUT Magic Value to Script dos, 2019-05-29
  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1532599 referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Mozilla Thunderbird
  • Mozilla Firefox ESR
  • Mozilla Firefox

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.