CVE-2016-4171: Adobe Flash Player unspecified remote code execution flaw

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 17 September 2026. Confidence: medium.

critical priorityCVSS 9.8, confirmed in-the-wild exploitation, and CISA KEV listing make this a critical priority despite the thin technical description.

What it is

CVE-2016-4171 is an unspecified vulnerability in Adobe Flash Player 21.0.0.242 and earlier that allows remote attackers to execute arbitrary code through unknown vectors. Adobe and CISA both confirm it was exploited in the wild in June 2016, and the record provides no root-cause detail beyond that. Because the flaw is remotely reachable with no privileges or user interaction per the CVSS vector, it is a serious risk anywhere Flash remains installed.

Impact

A successful attack lets a remote attacker run arbitrary code in the context of the Flash Player process, which typically means full compromise of the affected host or browser session. The record does not specify the exact code-execution primitive or any secondary impact such as data theft or persistence.

Attack surface

The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N, so the flaw is network-reachable, requires no authentication and no user interaction. The description says only 'unknown vectors', so the precise delivery path (for example a malicious SWF or web page) is not stated in the record.

Exploitation

CVE-2016-4171 is listed in CISA KEV (added 2022-03-25) and the description states it was exploited in the wild in June 2016. EPSS gives a 30-day probability of 0.20211 at the 97.3rd percentile, indicating elevated likelihood of exploitation activity.

What to do

• Apply the Adobe Flash Player update referenced in Adobe advisory APSB16-18 (or the corresponding Red Hat, SUSE, openSUSE or Gentoo errata) to any system still running Flash.
• Because Flash Player is end-of-life, remove or disable the plugin entirely and disconnect affected systems as CISA's KEV required action states.
• Block Flash content at the browser and network layer, and restrict outbound access to untrusted sites that could deliver a malicious SWF.
• Inventory hosts and browsers still carrying Flash Player 21.0.0.242 or earlier and prioritize them for remediation or decommissioning.

Detection

• Hunt for Flash Player versions at or below 21.0.0.242 across endpoints and browsers using software inventory or file-version checks.
• Monitor for unexpected child processes spawned by browser or Flash Player processes, which can indicate code execution from a malicious SWF.
• Review proxy, IDS and DNS logs for requests to known malicious SWF or exploit-kit hosts around the June 2016 exploitation window and later.
• Alert on Flash Player crashes or abnormal memory behavior on hosts that still have the plugin enabled.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.