CVE-2015-3113: Adobe Flash Player Heap-Based Buffer Overflow Vulnerability

CVE-2015-3113 is a heap-based buffer overflow in Adobe Flash Player that can let a remote attacker run code on a vulnerable system. Flash was once embedded widely in browsers and desktop applications, so any remaining installations still present a serious risk of compromise if content that triggers the flaw is opened.

CISA notes that the impacted product is end-of-life and should be disconnected if it is still in use. Teams that have not fully removed Flash should treat this as an urgent inventory and isolation problem rather than a routine patch cycle.

How it works

The weakness is classified as CWE-119: improper restriction of operations within the bounds of a memory buffer. In a heap-based buffer overflow, the application writes more data into a heap-allocated buffer than that buffer can hold. The excess data can corrupt adjacent memory structures that the process later uses for control flow or data handling.

An attacker who can supply specially crafted Flash content—typically delivered through a web page, malicious advertisement, or document that embeds the player—can cause the overflow. Successful abuse may allow arbitrary code execution in the context of the Flash process or the host application that loads it. Exact trigger conditions and exploit mechanics are not detailed here; confirm any technical specifics against the vendor advisory.

Am I affected? How to find it in your systems

Adobe Flash Player historically ran as a browser plugin, an ActiveX control, an NPAPI/PPAPI module, or a standalone projector on Windows, macOS, and Linux endpoints, and occasionally inside enterprise applications or kiosks that embedded the runtime. Because the product is end-of-life, any remaining copy is out of support.

Practical discovery steps:

• Inventory endpoints and application packages for Flash Player binaries, installer remnants, or browser plugin entries (for example, via software inventory, SCCM/Intune, or package managers).
• Search for common Flash-related file and registry artifacts and for processes that load Flash libraries.
• Check browser configurations and group policies that may still allow or auto-load legacy plugins.
• Review web proxy, DNS, and endpoint logs for attempts to retrieve Flash content (.swf) or for crashes and faulting modules associated with the Flash process—these can be secondary indicators but are not definitive proof of exploitation.

Confirm exact affected builds and any configuration caveats against the original vendor advisory; do not rely on version lists that are not taken from that source.

How to remediate

The primary remediation is to remove Adobe Flash Player entirely. CISA’s required action is that the impacted product is end-of-life and should be disconnected if still in use. Uninstall the runtime from all managed and unmanaged systems, revoke any enterprise packages that still distribute it, and ensure browsers no longer load the plugin.

After removal:

• Enforce policies that block Flash content at the browser, proxy, or email gateway.
• Replace any internal business applications that still depend on Flash with supported alternatives.
• Verify that automatic updates or legacy software catalogs cannot reinstall the player.

If a vendor-supplied update was ever issued for this CVE while Flash was supported, apply only the update named in the official advisory; for an end-of-life product, removal remains the durable fix.

If you can't patch immediately

When immediate uninstall is blocked by a legacy dependency, reduce exposure until removal is possible:

• Isolate systems that still have Flash on restricted network segments with no general internet access.
• Disable the Flash plugin and related MIME/type handlers in every browser and document viewer; prefer enterprise policies that prevent re-enablement.
• Block .swf and related Flash content at web proxies, secure web gateways, and email filters.
• Apply virtual patching or IPS/WAF rules that target known Flash exploit patterns only if your security vendor provides signatures tied to this class of issue; treat them as temporary.
• Increase monitoring on those hosts for process crashes, unusual child processes spawned by browser or Flash components, and outbound connections after Flash content is rendered.

These controls do not eliminate the vulnerability; they only lower the chance of successful remote exploitation until the software is gone.

If your data may have been exposed

Actively exploited remote-code-execution flaws in widely deployed runtimes have historically led to full host compromise and follow-on data theft. Ransomware use of this specific CVE is not documented in the provided facts, but any successful code execution can still enable credential theft, lateral movement, or exfiltration. If you have reason to believe systems were exposed, follow your incident-response process: isolate affected hosts, preserve volatile evidence, rotate credentials, and hunt for persistence. You can also run a free exposure scan of your email addresses against known breach data to see whether associated accounts appear in prior dumps while you complete containment and eradication.