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Flash PlayerApplication · Adobe

CVE-2016-4121

CRITICAL · 9.8 CVSS v3.1 Published 2016-06-16
Fix available
A fix is available. Upgrade to after 21.0.0.241 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Use-after-free vulnerability in Adobe Flash Player before 18.0.0.352 and 19.x through 21.x before 21.0.0.242 on Windows and OS X and before 11.2.202.621 on Linux allows attackers to execute arbitrary code via unspecified vectors, a different vulnerability than CVE-2016-1097, CVE-2016-1106, CVE-2016-1107, CVE-2016-1108, CVE-2016-1109, CVE-2016-1110, CVE-2016-4108, and CVE-2016-4110.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-416

Memory is used after it has been freed, so its contents — now potentially attacker-controlled — drive the program's behaviour. With careful heap grooming this becomes code execution. The fix requires disciplined ownership of memory and often a targeted rework of the object lifecycle.

General guidance for the use after free class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Flash PlayerApplication
Affected:<= 21.0.0.241<= 18.0.0.343<= 11.2.202.616<= 21.0.0.216
Air Sdk \& CompilerApplication
Affected:<= 21.0.0.198
Air SdkApplication
Affected:<= 21.0.0.198
Flash Player Desktop RuntimeApplication
Affected:<= 21.0.0.226
Air Desktop RuntimeApplication
Affected:<= 21.0.0.198

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 21.0.0.241
Vendor patch helpx.adobe.com →
Recommended fix High confidence

Flash Player 18.0.0.352 (18.x branch), 21.0.0.242 (19.x-21.x branch), or 11.2.202.621 (Linux 11.x); Air SDK/Compiler 21.0.0.217 or later

  1. 1. Identify the exact Flash Player version currently installed by navigating to about:flash in the browser or checking Help > About Adobe Flash Player
  2. 2. Determine which branch version is installed (18.x, 21.x, or 11.x for Linux) to select the correct fixed version
  3. 3. Download the appropriate patched version from the Adobe security bulletin at https://helpx.adobe.com/security/products/flash-player/apsb16-15.html
  4. 4. For Flash Player 18.x branch: upgrade to version 18.0.0.352
  5. 5. For Flash Player 19.x-21.x branch: upgrade to version 21.0.0.242
  6. 6. For Flash Player 11.x (Linux): upgrade to version 11.2.202.621
  7. 7. For Air SDK/Compiler versions <= 21.0.0.198: upgrade to version 21.0.0.217 or later as specified in the Adobe bulletin
  8. 8. Verify the installation by checking the Flash Player version again after patching
Caveat Flash Player reached end-of-life on December 31, 2020 - no further security patches will be released; migrating to HTML5-based alternatives is strongly recommended

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-4121 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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