---
id: "CVE-2015-5123"
kind: "vulnerability"
aliases: ["CVE-2015-5123"]
title: "Adobe Flash Player: Adobe Flash Player Use-After-Free Vulnerability"
severity: "critical"
cvss: 10.0
epss: 0.1883
exploited: true
status: "open"
category: "runtime"
products: [{"name": "Adobe Flash Player", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["adobe-flash-player", "browsers", "exploited", "macos", "runtime", "windows"]
not_affected_if: ["flash-not-installed", "managed-hosting"]
published_at: "2015-07-14T10:59:01+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2015-5123", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2015-5123", "first_seen_at": "2026-10-23T19:13:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2015-5123", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Adobe Flash Player: Adobe Flash Player Use-After-Free Vulnerability

Adobe Flash Player has a use-after-free bug in the BitmapData class of its ActionScript 3 code, which lets a remote attacker run code or crash the player. CISA lists it as actively exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Adobe Flash Player affected ? fixed ?

## How to check

Check whether any browser or machine has Adobe Flash Player installed, for example by looking for FlashPlayer plugin files or the Flash Player entry in installed software; the sources do not give a specific path.

## Fix

Remove Adobe Flash Player, since the product is end-of-life and CISA says to disconnect it if still in use; no supported patched version is named in the sources.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2015-5123
- 2026-10-23T19:13:45+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2015-5123
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2015-5123

## From the sources

Use-after-free vulnerability in the BitmapData class in the ActionScript 3 (AS3) implementation in Adobe Flash Player 13.x through 13.0.0.302 on Windows and OS X, 14.x through 18.0.0.203 on Windows and OS X, 11.x through 11.2.202.481 on Linux, and 12.x through 18.0.0.204 on Linux Chrome installations allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted Flash content that overrides a valueOf function, as exploited in the wild in July 2015.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_