CVE-2019-9800 — Mozilla: Memory safety bugs fixed in Firefox 67 and Firefox ESR 60.7

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CRITICAL

Mozilla: Memory safety bugs fixed in Firefox 67 and Firefox ESR 60.7

Published Jul 23, 2019

9.8

CRITICAL

CVSS 3.0

EPSS 1.73%

Description

Mozilla developers and community members reported memory safety bugs present in Firefox 66, Firefox ESR 60.6, and Thunderbird 60.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

Affected products

Vendor Mozilla Product Firefox Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <67
Vendor Mozilla Product Firefox ESR Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <60.7
Vendor Mozilla Product Thunderbird Default
n/a
- Version
  unspecified
  Status
  affected
  Constraints
  <60.7

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	<67

Mozilla

Firefox ESR

n/a

Version	Status	Constraints
unspecified	affected	<60.7

Mozilla

Thunderbird

n/a

Version	Status	Constraints
unspecified	affected	<60.7

Red Hat Enterprise Linux 6

firefox-0:60.7.0-1.el6_10

Fixed · RHSA-2019:1267
Red Hat Enterprise Linux 6

thunderbird-0:60.7.0-1.el6_10

Fixed · RHSA-2019:1310
Red Hat Enterprise Linux 7

firefox-0:60.7.0-1.el7_6

Fixed · RHSA-2019:1265
Red Hat Enterprise Linux 7

thunderbird-0:60.7.0-1.el7_6

Fixed · RHSA-2019:1309
Red Hat Enterprise Linux 8

firefox-0:60.7.0-1.el8_0

Fixed · RHSA-2019:1269
Red Hat Enterprise Linux 8

thunderbird-0:60.7.0-1.el8_0

Fixed · RHSA-2019:1308

Product	Package	State	Advisory
Red Hat Enterprise Linux 6	firefox-0:60.7.0-1.el6_10	Fixed	RHSA-2019:1267
Red Hat Enterprise Linux 6	thunderbird-0:60.7.0-1.el6_10	Fixed	RHSA-2019:1310
Red Hat Enterprise Linux 7	firefox-0:60.7.0-1.el7_6	Fixed	RHSA-2019:1265
Red Hat Enterprise Linux 7	thunderbird-0:60.7.0-1.el7_6	Fixed	RHSA-2019:1309
Red Hat Enterprise Linux 8	firefox-0:60.7.0-1.el8_0	Fixed	RHSA-2019:1269
Red Hat Enterprise Linux 8	thunderbird-0:60.7.0-1.el8_0	Fixed	RHSA-2019:1308

Remediation

Red Hat statement

In general, this flaw cannot be exploited through email in Thunderbird because scripting is disabled when reading mail, but it is potentially a risk in browser or browser-like contexts.

Metrics

1.73% 0.01726

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.01726

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 (16 key points)

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

Date	Score	Percentile	Model
Oct 1, 2026	1.73% (0.01726)	76.71th	v5 (v2026.06.15)
Jun 15, 2026	1.77% (0.01775)	75.23th	v5 (v2026.06.15)
Mar 30, 2025	0.55% (0.00554)	65.45th	v4 (v2025.03.14)
Mar 29, 2025	2.09% (0.02089)	73.36th	v4 (v2025.03.14)
Jul 20, 2024	0.62% (0.00622)	79.10th	v3 (v2023.03.01)
Jul 16, 2024	0.62% (0.00622)	79.08th	v3 (v2023.03.01)
Feb 8, 2024	0.61% (0.00611)	77.99th	v3 (v2023.03.01)
Sep 3, 2023	0.61% (0.00611)	75.98th	v3 (v2023.03.01)
Mar 7, 2023	0.37% (0.00372)	68.35th	v3 (v2023.03.01)
Mar 6, 2023	1.02% (0.01018)	40.69th	v2 (v2022.01.01)
Apr 1, 2022	1.02% (0.01018)	36.86th	v2 (v2022.01.01)
Feb 4, 2022	15.35% (0.15351)	91.59th	v2 (v2022.01.01)
Feb 3, 2022	3.71% (0.03706)	72.25th	v1
Jan 6, 2022	3.71% (0.03706)	72.01th	v1
Jan 5, 2022	0.85% (0.00850)	59.68th	v5 (v2026.06.15)
Apr 14, 2021	0.85% (0.00850)	0.00th	v1

Weaknesses (2)

CWE-120

Classic Buffer Overflow

CWE-787

Out-of-bounds Write

References (9)

https://access.redhat.com/security/cve/CVE-2019-9800
Vendor Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1540166%2C1534593%2C1546327%2C1540136%2C1538736%2C1538042%2C1535612%2C1499719%2C1499108%2C1538619%2C1535194%2C1516325%2C1542324%2C1542097%2C1532465%2C1533554%2C1541580
x_refsource_MISCPermissions Required
https://bugzilla.redhat.com/show_bug.cgi?id=1712623
Issue Tracking
https://nvd.nist.gov/vuln/detail/CVE-2019-9800
https://www.cve.org/CVERecord?id=CVE-2019-9800
https://www.mozilla.org/en-US/security/advisories/mfsa2019-14/#CVE-2019-9800
https://www.mozilla.org/security/advisories/mfsa2019-13/
x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-14/
x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-15/
x_refsource_MISCVendor Advisory

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2019-9800		Vendor Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1540166%2C1534593%2C1546327%2C1540136%2C1538736%2C1538042%2C1535612%2C1499719%2C1499108%2C1538619%2C1535194%2C1516325%2C1542324%2C1542097%2C1532465%2C1533554%2C1541580		x_refsource_MISCPermissions Required
https://bugzilla.redhat.com/show_bug.cgi?id=1712623		Issue Tracking
https://nvd.nist.gov/vuln/detail/CVE-2019-9800
https://www.cve.org/CVERecord?id=CVE-2019-9800
https://www.mozilla.org/en-US/security/advisories/mfsa2019-14/#CVE-2019-9800
https://www.mozilla.org/security/advisories/mfsa2019-13/		x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-14/		x_refsource_MISCVendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-15/		x_refsource_MISCVendor Advisory