CVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerability

Q: How do I fix CVE-2019-11707?

firefox: upgrade to 60.7.1, 67.0.3; thunderbird: upgrade to 60.7.2. Exact commands for each OS are on this page.

Q: Is CVE-2019-11707 being exploited?

Yes. CVE-2019-11707 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2019-11707 affect?

CVE-2019-11707 affects firefox, thunderbird. Severity is high (CVSS 8.8). A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Fi

Q: How urgent is CVE-2019-11707?

Priority 85/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference

Patch now

HIGH 8.8EXPLOITEDUPGRADEUPGRADE

CVE-2019-11707 is a high-severity flaw (CVSS 8.8) affecting firefox, thunderbird, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1, Firefox < 67.0.3, and Thunderbird < 60.7.2.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	38.0% (top 1%)
CISA exploited list	Yes, fix due 2022-06-13
Weakness	CWE-843
Published	2019-07-23
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: mozilla

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-07-23 14:15 UTCPublished CVE record published
2022-05-23Exploited Added to the CISA Known Exploited Vulnerabilities list
2022-06-13Deadline CISA due date for US federal agencies to patch
2026-06-17 02:13 UTCUpdated Record last modified

mozilla firefox UPGRADE

Affected: < 60.7.1 · < 67.0.3

Fixed in: 60.7.1, 67.0.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy firefox || rpm -q firefox || firefox --version

2. UPGRADE to 60.7.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade firefox

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

mozilla thunderbird UPGRADE

Affected: < 60.7.2

Fixed in: 60.7.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy thunderbird || rpm -q thunderbird || thunderbird --version

2. UPGRADE to 60.7.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade thunderbird

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade thunderbird

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora ELN · python-discovery · FIXED · 1.9.0-1.eln159 · FEDORA-2026-7a881c0c99 · source

sudo dnf upgrade --advisory=FEDORA-2026-7a881c0c99

Fedora 46 · pipx · FIXED · 1.18.11-1.fc46 · FEDORA-2026-443a765287 · source

sudo dnf upgrade --advisory=FEDORA-2026-443a765287

Ubuntu 20.04 · firefox · FIXED · 67.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "67.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · firefox · FIXED · 67.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "67.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · firefox · FIXED · 67.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "67.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · thunderbird · FIXED · 1:60.7.2+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:60.7.2+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · thunderbird · FIXED · 1:60.7.2+build1-0ubuntu1

Debian 12 · firefox-esr · FIXED · 60.7.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "60.7.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 60.7.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "60.7.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · thunderbird · FIXED · 1:60.7.2-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:60.7.2-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · thunderbird · FIXED · 1:60.7.2-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:60.7.2-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 6 · firefox · FIXED · firefox-60.7.2-1.el6_10

sudo dnf upgrade --advisory=RHSA-2019:1604 rpm -q firefox

RHEL 6 · thunderbird · FIXED · thunderbird-60.7.2-2.el6_10

sudo dnf upgrade --advisory=RHSA-2019:1624 rpm -q thunderbird

RHEL 7 · firefox · FIXED · firefox-60.7.2-1.el7_6

sudo dnf upgrade --advisory=RHSA-2019:1603 rpm -q firefox

RHEL 7 · thunderbird · FIXED · thunderbird-60.7.2-2.el7_6

sudo dnf upgrade --advisory=RHSA-2019:1626 rpm -q thunderbird

RHEL 8 · thunderbird · FIXED · thunderbird-60.7.2-2.el8_0

sudo dnf upgrade --advisory=RHSA-2019:1623 rpm -q thunderbird

Alpine 3.20 · firefox-esr · FIXED · firefox-esr-60.7.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.21 · firefox-esr · FIXED · firefox-esr-60.7.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.22 · firefox-esr · FIXED · firefox-esr-60.7.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Alpine 3.23 · firefox-esr · FIXED · firefox-esr-60.7.1-r0

apk add --upgrade firefox-esr apk info -v firefox-esr

Amazon Linux 2 · see advisory · FIXED · ALAS2-2019-1250 · source

sudo yum update --advisory=ALAS2-2019-1250

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: vigneshsrao/CVE-2019-11707 (42 stars)
GitHub PoC: flabbergastedbd/cve-2019-11707 (2 stars)
GitHub PoC: CosminGGeorgescu/CVE-2019-11707-PoC (0 stars)
Write-up: bugzilla.mozilla.org/show_bug.cgi?id=1544386
GitHub PoC: tunnelshade/cve-2019-11707
Exploit-DB: Mozilla Spidermonkey - IonMonkey 'Array.prototype.pop' Type Confusion
Exploit-DB: Mozilla Firefox 67 - Array.pop JIT Type Confusion

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2019-11707?

firefox: upgrade to 60.7.1, 67.0.3; thunderbird: upgrade to 60.7.2. Exact commands for each OS are on this page.

Is CVE-2019-11707 being exploited?

Yes. CVE-2019-11707 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2019-11707 affect?

CVE-2019-11707 affects firefox, thunderbird. Severity is high (CVSS 8.8). A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Fi

How urgent is CVE-2019-11707?

Priority 85/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference

Software pages

Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

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References

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