CVE-2016-9079: Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerability

Q: How do I fix CVE-2016-9079?

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

Q: Is CVE-2016-9079 being exploited?

Yes. CVE-2016-9079 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2016-9079 affect?

CVE-2016-9079 affects debian linux, enterprise linux, enterprise linux desktop. Severity is high (CVSS 7.5). A use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Fir

Q: How urgent is CVE-2016-9079?

Priority 91/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Patch now

HIGH 7.5EXPLOITEDREMOTEWATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2016-9079 is a high-severity flaw (CVSS 7.5) affecting debian linux, enterprise linux, enterprise linux desktop, 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 use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Firefox ESR < 45.5.1, and Thunderbird < 45.5.1.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	87.4% (top 1%)
CISA exploited list	Yes, fix due 2023-07-13
Weakness	CWE-416
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
2023-06-22Exploited Added to the CISA Known Exploited Vulnerabilities list
2023-07-13Deadline CISA due date for US federal agencies to patch
2026-06-17 00:55 UTCUpdated Record last modified

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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 MITIGATE

Affected: 5.0 · 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

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: 5.0 · 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

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: 5.0 · 6.0 · 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

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: 7.3 · 7.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.3

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: 7.3 · 7.4 · 7.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.3

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 · 45.5.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "45.5.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 45.5.1esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "45.5.1esr-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 5 · firefox · FIXED · firefox-45.5.1-1.el5_11

sudo dnf upgrade --advisory=RHSA-2016:2843 rpm -q firefox

RHEL 5 · thunderbird · FIXED · thunderbird-45.5.1-1.el5_11

sudo dnf upgrade --advisory=RHSA-2016:2850 rpm -q thunderbird

RHEL 6 · firefox · FIXED · firefox-45.5.1-1.el6_8

sudo dnf upgrade --advisory=RHSA-2016:2843 rpm -q firefox

RHEL 6 · thunderbird · FIXED · thunderbird-45.5.1-1.el6_8

sudo dnf upgrade --advisory=RHSA-2016:2850 rpm -q thunderbird

RHEL 7 · firefox · FIXED · firefox-45.5.1-1.el7_3

sudo dnf upgrade --advisory=RHSA-2016:2843 rpm -q firefox

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: dangokyo/CVE-2016-9079 (7 stars)
GitHub PoC: LakshmiDesai/CVE-2016-9079 (1 stars)
GitHub PoC: soham23/firefox-rce-nssmil (1 stars)
Write-up: bugzilla.mozilla.org/show_bug.cgi?id=1321066
Write-up: www.exploit-db.com/exploits/41151/
Exploit-DB: Firefox 50.0.1 - ASM.JS JIT-Spray Remote Code Execution
Exploit-DB: Mozilla Firefox < 50.0.2 - 'nsSMILTimeContainer::NotifyTimeChange()' Remote Code Execution (Metasploit)
Metasploit: Firefox nsSMILTimeContainer::NotifyTimeChange() RCE

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-2016-9079?

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

Is CVE-2016-9079 being exploited?

Yes. CVE-2016-9079 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2016-9079 affect?

CVE-2016-9079 affects debian linux, enterprise linux, enterprise linux desktop. Severity is high (CVSS 7.5). A use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Fir

How urgent is CVE-2016-9079?

Priority 91/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Windows vulnerabilities · Debian vulnerabilities · Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

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References

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