CVE-2018-5159: An integer overflow can occur in the Skia library due to 32-bit integer use in an array without integer overfl

Q: How do I fix CVE-2018-5159?

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

Q: Is CVE-2018-5159 being exploited?

CVE-2018-5159 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-2018-5159 affect?

CVE-2018-5159 affects debian linux, enterprise linux desktop, enterprise linux server. Severity is critical (CVSS 9.8). An integer overflow can occur in the Skia library due to 32-bit integer use in an array without integer overflow checks, resulting in possible out-of-bounds writes. This could lead to a potentially exploitable crash triggerable by web conte

Q: How urgent is CVE-2018-5159?

Priority 74/100. Critical severity; EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2018-5159 is a critical-severity flaw (CVSS 9.8) affecting debian linux, enterprise linux desktop, enterprise linux server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An integer overflow can occur in the Skia library due to 32-bit integer use in an array without integer overflow checks, resulting in possible out-of-bounds writes. This could lead to a potentially exploitable crash triggerable by web content. This vulnerability affects Thunderbird < 52.8, Thunderbird ESR < 52.8, Firefox < 60, and Firefox ESR < 52.8.

Why this priority

Critical severity
EPSS top 2%: 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	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	20.6% (top 2%)
CISA exploited list	No
Weakness	CWE-190, CWE-787
Published	2018-06-11
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: debian · redhat

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

Am I affected?

Timeline

2018-06-11 21:29 UTCPublished CVE record published
2026-06-17 01:59 UTCUpdated Record last modified

debian debian linux MITIGATE

Affected: 7.0 · 8.0 · 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

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 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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · librepo · FIXED · 1.21.3-1.fc46 · FEDORA-2026-c502136ca7 · source

sudo dnf upgrade --advisory=FEDORA-2026-c502136ca7

Debian 12 · firefox-esr · FIXED · 52.8.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "52.8.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 52.8.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "52.8.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · thunderbird · FIXED · 1:52.8.0-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:52.8.0-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · thunderbird · FIXED · 1:52.8.0-1

sudo apt update && sudo apt install --only-upgrade thunderbird dpkg --compare-versions "$(dpkg-query -W -f='${Version}' thunderbird)" ge "1:52.8.0-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 6 · firefox · FIXED · firefox-52.8.0-1.el6_9

sudo dnf upgrade --advisory=RHSA-2018:1414 rpm -q firefox

RHEL 6 · thunderbird · FIXED · thunderbird-52.8.0-2.el6_9

sudo dnf upgrade --advisory=RHSA-2018:1726 rpm -q thunderbird

RHEL 7 · firefox · FIXED · firefox-52.8.0-1.el7_5

sudo dnf upgrade --advisory=RHSA-2018:1415 rpm -q firefox

RHEL 7 · thunderbird · FIXED · thunderbird-52.8.0-1.el7_5

sudo dnf upgrade --advisory=RHSA-2018:1725 rpm -q thunderbird

RHEL 8 · firefox · NOT AFFECTED

Amazon Linux 2 · see advisory · FIXED · ALAS2-2018-1032 · source

sudo yum update --advisory=ALAS2-2018-1032

Public exploits and detection

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

Write-up: bugzilla.mozilla.org/show_bug.cgi?id=1441941
Write-up: www.exploit-db.com/exploits/44759/
Exploit-DB: Skia and Firefox - Integer Overflow in SkTDArray Leading to Out-of-Bounds Write

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-2018-5159?

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

Is CVE-2018-5159 being exploited?

CVE-2018-5159 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-2018-5159 affect?

CVE-2018-5159 affects debian linux, enterprise linux desktop, enterprise linux server. Severity is critical (CVSS 9.8). An integer overflow can occur in the Skia library due to 32-bit integer use in an array without integer overflow checks, resulting in possible out-of-bounds writes. This could lead to a potentially exploitable crash triggerable by web conte

How urgent is CVE-2018-5159?

Priority 74/100. Critical severity; EPSS top 2%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

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References

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