critical 9.8

CVE-2019-9791 in the critical feed json

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled throug…

published 2019-04-26 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-19153

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 19.9%; EPSS 19.9% chance of exploitation in 30 days, percentile 97%
public exploits: 1; Exploit-DB

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Patch / fix

fixed in 3 distros 7

Mozilla Thunderbird 60.6
Mozilla Firefox ESR 60.6
Mozilla Firefox 66

debian ubuntu red hat suse opensuse alpine arch linux

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-2019-9791

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-2019-9791

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-2019:1144 RHSA-2019:0681 RHSA-2019:0966 RHSA-2019:0680 RHSA-2019:0623 RHSA-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-2019:0871-1 SUSE-SU-2019:0853-1 SUSE-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-2024:14572-1 openSUSE-SU-2024:10600-1 openSUSE-SU-2019:1162-1 openSUSE-SU-2019:1126-1 openSUSE-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-2019-9791

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-2019-9791 updated 2026-11-04 cvss 9.8

Mozilla: Type inference is incorrect for constructors entered through on-stack replacement with IonMonkey

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

2019-03-26 First public exploit (EDB-46613)
2019-04-26 Published

Exploit prediction

19.91% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

EDB-46613 Spidermonkey - IonMonkey Type Inference is Incorrect for Constructors Entered via OSR dos, 2019-03-26
bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=1530958 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

CWE-843 Access of Resource Using Incompatible Type

References

bugzilla.mozilla.org /show_bug.cgi?id=1530958
exploit, issue-tracking, vendor-advisory
access.redhat.com /errata/RHSA-2019:0966
vendor-advisory, third-party-advisory
access.redhat.com /errata/RHSA-2019:1144
vendor-advisory, third-party-advisory
mozilla.org /security/advisories/mfsa2019-07/
vendor-advisory
mozilla.org /security/advisories/mfsa2019-08/
vendor-advisory
mozilla.org /security/advisories/mfsa2019-11/
vendor-advisory

Sources

CVE List CVE-2019-9791
NVD CVE-2019-9791

Fencer Vulns 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.

Summary