CVE-2019-9795 — Mozilla: Type-confusion in IonMonkey JIT compiler

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CRITICAL

Mozilla: Type-confusion in IonMonkey JIT compiler

Published Apr 26, 2019

9.8

CRITICAL

CVSS 3.0

EPSS 1.70%

Description

A vulnerability where type-confusion in the IonMonkey just-in-time (JIT) compiler could potentially be used by malicious JavaScript to trigger a potentially exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Affected products

Vendor Mozilla Product Firefox Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <66
Vendor Mozilla Product Firefox ESR Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <60.6
Vendor Mozilla Product Thunderbird Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <60.6

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Mozilla

Firefox

n/a

Version	Status	Constraints
unspecified	affected	<66

Mozilla

Firefox ESR

n/a

Version	Status	Constraints
unspecified	affected	<60.6

Mozilla

Thunderbird

n/a

Version	Status	Constraints
unspecified	affected	<60.6

Red Hat Enterprise Linux 6

firefox-0:60.6.0-3.el6_10

Fixed · RHSA-2019:0623
Red Hat Enterprise Linux 6

thunderbird-0:60.6.1-1.el6_10

Fixed · RHSA-2019:0680
Red Hat Enterprise Linux 7

firefox-0:60.6.0-3.el7_6

Fixed · RHSA-2019:0622
Red Hat Enterprise Linux 7

thunderbird-0:60.6.1-1.el7_6

Fixed · RHSA-2019:0681
Red Hat Enterprise Linux 8

firefox-0:60.6.1-1.el8

Fixed · RHSA-2019:0966
Red Hat Enterprise Linux 8

thunderbird-0:60.6.1-1.el8

Fixed · RHSA-2019:1144

Product	Package	State	Advisory
Red Hat Enterprise Linux 6	firefox-0:60.6.0-3.el6_10	Fixed	RHSA-2019:0623
Red Hat Enterprise Linux 6	thunderbird-0:60.6.1-1.el6_10	Fixed	RHSA-2019:0680
Red Hat Enterprise Linux 7	firefox-0:60.6.0-3.el7_6	Fixed	RHSA-2019:0622
Red Hat Enterprise Linux 7	thunderbird-0:60.6.1-1.el7_6	Fixed	RHSA-2019:0681
Red Hat Enterprise Linux 8	firefox-0:60.6.1-1.el8	Fixed	RHSA-2019:0966
Red Hat Enterprise Linux 8	thunderbird-0:60.6.1-1.el8	Fixed	RHSA-2019:1144

Remediation

Red Hat 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.

Metrics

1.70% 0.01699

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.

EPSS probability 0.01699

Score over time

2021–2026

EPSS v1
EPSS v5
EPSS v2
EPSS v3
EPSS v4

Percentile over time

EPSS v1
EPSS v5
EPSS v2
EPSS v3
EPSS v4

Table of values (15 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 2, 2026	1.70% (0.01699)	76.38th	v5 (v2026.06.15)
Jun 15, 2026	1.70% (0.01699)	74.13th	v5 (v2026.06.15)
Mar 30, 2025	1.16% (0.01163)	76.67th	v4 (v2025.03.14)
Mar 29, 2025	3.19% (0.03194)	78.18th	v4 (v2025.03.14)
Jul 20, 2024	0.89% (0.00892)	82.81th	v3 (v2023.03.01)
Apr 19, 2024	0.89% (0.00892)	82.42th	v3 (v2023.03.01)
Sep 3, 2023	0.82% (0.00824)	79.77th	v3 (v2023.03.01)
Mar 7, 2023	0.76% (0.00762)	78.31th	v3 (v2023.03.01)
Mar 6, 2023	1.11% (0.01108)	55.18th	v2 (v2022.01.01)
Apr 1, 2022	1.11% (0.01108)	51.54th	v2 (v2022.01.01)
Feb 4, 2022	12.30% (0.12300)	89.42th	v2 (v2022.01.01)
Feb 3, 2022	6.21% (0.06208)	81.93th	v1
Jan 6, 2022	6.21% (0.06208)	81.75th	v1
Jan 5, 2022	1.45% (0.01454)	72.86th	v5 (v2026.06.15)
Apr 14, 2021	1.45% (0.01454)	0.00th	v1

Weaknesses (2)

CWE-617

CWE-843

References (11)

https://access.redhat.com/errata/RHSA-2019:0966
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2019:1144
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2019-9795
Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1514682
x_refsource_MISCIssue TrackingPermissions RequiredVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1690680
Issue Tracking
https://nvd.nist.gov/vuln/detail/CVE-2019-9795
https://www.cve.org/CVERecord?id=CVE-2019-9795
https://www.mozilla.org/en-US/security/advisories/mfsa2019-08/#CVE-2019-9795
https://www.mozilla.org/security/advisories/mfsa2019-07/
x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/
x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/
x_refsource_MISCVendor Advisory

Link	Providers	Tags
https://access.redhat.com/errata/RHSA-2019:0966		vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2019:1144		vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2019-9795		Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1514682		x_refsource_MISCIssue TrackingPermissions RequiredVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1690680		Issue Tracking
https://nvd.nist.gov/vuln/detail/CVE-2019-9795
https://www.cve.org/CVERecord?id=CVE-2019-9795
https://www.mozilla.org/en-US/security/advisories/mfsa2019-08/#CVE-2019-9795
https://www.mozilla.org/security/advisories/mfsa2019-07/		x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/		x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/		x_refsource_MISCVendor Advisory