CVE-2016-4171: Adobe Flash Player Remote Code Execution Vulnerability

Q: How do I fix CVE-2016-4171?

flash player: upgrade to newer than 21.0.0.242; flash player: upgrade to newer than 21.0.0.242; flash player: upgrade to newer than 21.0.0.242. Exact commands for each OS are on this page.

Q: Is CVE-2016-4171 being exploited?

Yes. CVE-2016-4171 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2016-4171 affect?

CVE-2016-4171 affects flash player, flash player, flash player. Severity is critical (CVSS 9.8). Unspecified vulnerability in Adobe Flash Player 21.0.0.242 and earlier allows remote attackers to execute arbitrary code via unknown vectors, as exploited in the wild in June 2016.

Q: How urgent is CVE-2016-4171?

Priority 94/100. Critical severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV); Remotely exploitable, no login, no user action; On your watchlist

Patch now

CRITICAL 9.8EXPLOITEDREMOTEWATCHLISTUPGRADEUPGRADEUPGRADE

CVE-2016-4171 is a critical-severity flaw (CVSS 9.8) affecting flash player, flash player, flash player, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Unspecified vulnerability in Adobe Flash Player 21.0.0.242 and earlier allows remote attackers to execute arbitrary code via unknown vectors, as exploited in the wild in June 2016.

Why this priority

Critical severity
EPSS top 3%: very likely to be exploited
Exploited in the wild (CISA KEV)
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	20.1% (top 3%)
CISA exploited list	Yes, fix due 2022-04-15
Published	2016-06-16
Last modified	2026-06-17

Publisher (CNA): Adobe Systems Incorporated · Vendor: adobe · redhat

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

Am I affected?

Timeline

2016-06-16 14:59 UTCPublished CVE record published
2022-03-25Exploited Added to the CISA Known Exploited Vulnerabilities list
2022-04-15Deadline CISA due date for US federal agencies to patch
2026-06-17 00:47 UTCUpdated Record last modified

adobe flash player UPGRADE

Affected: <= 11.2.202.621 · <= 21.0.0.242 · <= 18.0.0.352

Fixed in: newer than 21.0.0.242

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy flash-player || rpm -q flash-player || flash-player --version

2. UPGRADE to newer than 21.0.0.242 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade flash-player

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flash-player

Note

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

adobe flash player UPGRADE

Affected: <= 21.0.0.242

Fixed in: newer than 21.0.0.242

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy flash-player || rpm -q flash-player || flash-player --version

2. UPGRADE to newer than 21.0.0.242 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade flash-player

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flash-player

Note

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

adobe flash player UPGRADE

Affected: <= 21.0.0.242

Fixed in: newer than 21.0.0.242

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy flash-player || rpm -q flash-player || flash-player --version

2. UPGRADE to newer than 21.0.0.242 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade flash-player

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flash-player

Note

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

adobe flash player UPGRADE

Affected: <= 21.0.0.242

Fixed in: newer than 21.0.0.242

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy flash-player || rpm -q flash-player || flash-player --version

2. UPGRADE to newer than 21.0.0.242 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade flash-player

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade flash-player

Note

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

redhat enterprise linux desktop MITIGATE

Affected: 5.0 · 6.0

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

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · perl-Net-IDN-Encode · FIXED · 2.600-1.fc46 · FEDORA-2026-84eff0ea64 · source

sudo dnf upgrade --advisory=FEDORA-2026-84eff0ea64

Fedora ELN · libXISF · FIXED · 0.2.15-2.eln159 · FEDORA-2026-b9e2d1bda0 · source

sudo dnf upgrade --advisory=FEDORA-2026-b9e2d1bda0

RHEL 5 Supplementary · flash-plugin · FIXED · flash-plugin-11.2.202.626-1.el5_11

sudo dnf upgrade --advisory=RHSA-2016:1238 rpm -q flash-plugin

RHEL 6 Supplementary · flash-plugin · FIXED · flash-plugin-11.2.202.626-1.el6_8

sudo dnf upgrade --advisory=RHSA-2016:1238 rpm -q flash-plugin

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-2016-4171?

flash player: upgrade to newer than 21.0.0.242; flash player: upgrade to newer than 21.0.0.242; flash player: upgrade to newer than 21.0.0.242. Exact commands for each OS are on this page.

Is CVE-2016-4171 being exploited?

Yes. CVE-2016-4171 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2016-4171 affect?

CVE-2016-4171 affects flash player, flash player, flash player. Severity is critical (CVSS 9.8). Unspecified vulnerability in Adobe Flash Player 21.0.0.242 and earlier allows remote attackers to execute arbitrary code via unknown vectors, as exploited in the wild in June 2016.

How urgent is CVE-2016-4171?

Priority 94/100. Critical severity; EPSS top 3%: very likely to be exploited; Exploited in the wild (CISA KEV); Remotely exploitable, no login, no user action; On your watchlist

Software pages

Adobe Flash vulnerabilities

Related CVEs

CVE-2018-15982 HIGH 7.8 EXPLOITED UPGRADE UPGRADE Adobe Flash Player Use-After-Free Vulnerability
CVE-2016-1019 CRITICAL 9.8 EXPLOITED UPGRADE UPGRADE Adobe Flash Player Arbitrary Code Execution Vulnerability
CVE-2016-4117 CRITICAL 9.8 EXPLOITED UPGRADE MITIGATE Adobe Flash Player Arbitrary Code Execution Vulnerability
CVE-2020-9746 HIGH 7.0 UPGRADE UPGRADE Adobe Flash Player version 32.0.0.433 (and earlier) are affected by an exploitable NULL pointer dereference vu
CVE-2020-9633 CRITICAL 9.8 UPGRADE UPGRADE Adobe Flash Player Desktop Runtime 32.0.0.371 and earlier, Adobe Flash Player for Google Chrome 32.0.0.371 and

References

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