CVE-2018-12387: A vulnerability where the JavaScript JIT compiler inlines Array.prototype.push with multiple arguments that re

Q: How do I fix CVE-2018-12387?

enterprise linux desktop: mitigate or apply the listed mitigation; enterprise linux server: mitigate or apply the listed mitigation; enterprise linux server aus: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2018-12387 being exploited?

CVE-2018-12387 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2018-12387 affect?

CVE-2018-12387 affects enterprise linux desktop, enterprise linux server, enterprise linux server aus. Severity is critical (CVSS 9.1). A vulnerability where the JavaScript JIT compiler inlines Array.prototype.push with multiple arguments that results in the stack pointer being off by 8 bytes after a bailout. This leaks a memory address to the calling function which can be

Q: How urgent is CVE-2018-12387?

Priority 71/100. Critical severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.1REMOTEWATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2018-12387 is a critical-severity flaw (CVSS 9.1) affecting enterprise linux desktop, enterprise linux server, enterprise linux server aus. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability where the JavaScript JIT compiler inlines Array.prototype.push with multiple arguments that results in the stack pointer being off by 8 bytes after a bailout. This leaks a memory address to the calling function which can be used as part of an exploit inside the sandboxed content process. This vulnerability affects Firefox ESR < 60.2.2 and Firefox < 62.0.3.

Why this priority

Critical severity
EPSS top 5%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	9.6% (top 5%)
CISA exploited list	No
Weakness	CWE-20
Published	2018-10-18
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: redhat

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

Am I affected?

Timeline

2018-10-18 13:29 UTCPublished CVE record published
2026-06-17 01:37 UTCUpdated Record last modified

redhat enterprise linux desktop MITIGATE

Affected: 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux server MITIGATE

Affected: 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux server aus MITIGATE

Affected: 7.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.6

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux server eus MITIGATE

Affected: 7.5 · 7.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.5

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux server tus MITIGATE

Affected: 7.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.6

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux workstation MITIGATE

Affected: 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · copyparty · FIXED · 1.20.26-1.fc46 · FEDORA-2026-8fbe18458e · source

sudo dnf upgrade --advisory=FEDORA-2026-8fbe18458e

Fedora ELN · man-pages · FIXED · 6.20-1.eln159 · FEDORA-2026-f1f5fb11b4 · source

sudo dnf upgrade --advisory=FEDORA-2026-f1f5fb11b4

Ubuntu 22.04 · firefox · FIXED · 62.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "62.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · firefox · FIXED · 62.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "62.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · firefox · FIXED · 62.0.3+build1-0ubuntu1

sudo apt update && sudo apt install --only-upgrade firefox dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox)" ge "62.0.3+build1-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · thunderbird · FIXED · 1:60.4.0+build2-0ubuntu1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:60.4.0+build2-0ubuntu1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · thunderbird · FIXED · 1:60.4.0+build2-0ubuntu1

Debian 12 · firefox-esr · FIXED · 60.2.2esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "60.2.2esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 60.2.2esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "60.2.2esr-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 6 · firefox · FIXED · firefox-60.2.2-1.el6

sudo dnf upgrade --advisory=RHSA-2018:2881 rpm -q firefox

RHEL 7 · firefox · FIXED · firefox-60.2.2-1.el7_5

sudo dnf upgrade --advisory=RHSA-2018:2884 rpm -q firefox

RHEL 6 · thunderbird · NOT AFFECTED

RHEL 7 · thunderbird · NOT AFFECTED

Verify at the official source NVD · CVE Program · 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-2018-12387?

enterprise linux desktop: mitigate or apply the listed mitigation; enterprise linux server: mitigate or apply the listed mitigation; enterprise linux server aus: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-12387 being exploited?

CVE-2018-12387 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-12387 affect?

CVE-2018-12387 affects enterprise linux desktop, enterprise linux server, enterprise linux server aus. Severity is critical (CVSS 9.1). A vulnerability where the JavaScript JIT compiler inlines Array.prototype.push with multiple arguments that results in the stack pointer being off by 8 bytes after a bailout. This leaks a memory address to the calling function which can be

How urgent is CVE-2018-12387?

Priority 71/100. Critical severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Mozilla Firefox vulnerabilities

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References

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