Is CVE-2013-0074 (Microsoft Silverlight Double Dereference) being exploited in the wild?

Yes. CISA added CVE-2013-0074 to its Known Exploited Vulnerabilities catalogue on 25 May 2022, which it does only when there is reliable evidence of active exploitation. CISA lists it as known to be used in ransomware campaigns. Microsoft Silverlight does not properly validate pointers during HTML object rendering, which allows remote attackers to execute code via a crafted Silverlight application.

How CISA’s KEV Listing Changes the Answer

CISA’s KEV catalogue is the key signal here because it reflects confirmed active exploitation, not just theoretical exposure. For CVE-2013-0074, that means defenders should treat the issue as live operational risk, then confirm whether any Silverlight-dependent applications remain reachable in the environment.

That distinction matters because a vulnerable component may still be present in browsers, legacy web applications, remote desktops or archived workflows even after the broader platform has faded from normal use. When a KEV entry is this old, the practical question is often not whether the flaw exists in the abstract, but whether any business process still depends on the affected rendering path.

What the Vulnerability Actually Enables

The flaw is a pointer-validation failure in Silverlight’s HTML object rendering path. In practice, that means a crafted Silverlight application can trigger memory corruption and lead to remote code execution if a user loads it in an exposed client context. The exploit path is still useful to understand even when the product is legacy, because old web plug-ins often persist in long-tail internal applications and kiosk-style environments.

For defenders, the important technical implication is that exploitation does not require account compromise first. If the application is reachable and the client still executes Silverlight content, the attacker can target the rendering flaw directly. That makes browser compatibility exceptions and legacy application exceptions especially important to inventory, because they are often the real exposure point.

How to Triage and Reduce Exposure

The fastest triage step is to identify where Silverlight is still enabled, required, or silently tolerated. If the affected application is no longer business-critical, removing access to the content path is usually safer than treating the issue as a patch-only problem. If the application must remain online, isolate it tightly and reduce the number of clients that can reach it.

For an exploited-in-the-wild flaw, the defensive priority is to limit exposure first, then verify whether the vulnerable path has been used recently. That usually means checking endpoint telemetry, browser history where available, proxy logs, EDR detections and any application logs that show access to the legacy content. If the application ran on a shared or privileged workstation, broaden the review to adjacent systems and saved user sessions.

Risk and Threat Considerations

Actively exploited legacy client flaws are high risk because they often sit behind trusted internal access paths and are triggered through ordinary web interaction. The danger is not only code execution, but also the possibility that an attacker uses the initial foothold to steal browser data, pivot to adjacent systems, or stage follow-on payloads in a less monitored part of the environment.

Failure mechanism: The vulnerable Silverlight rendering path accepts crafted content that can corrupt memory and execute attacker-controlled code on the client.

Impact: A successful exploit can give the attacker code execution in the user context, which may become a stepping stone to data theft, persistence or broader internal compromise if the client is highly trusted.

Practitioner Guidance

What to verify: Confirm whether any production, test or archival application still depends on Silverlight, then check whether those paths are reachable from standard user workstations or privileged admin environments. If the answer is yes, treat the exposure as more than a patching issue.

Decision rule: If the vulnerable content can be removed or replaced, do that first. If it cannot, contain it with access restriction, client hardening and aggressive monitoring, because a KEV-listed issue should not be left as an assumed exception.

Practitioner takeaway: For exploited legacy plug-in flaws, the real control question is not whether the product is obsolete, but whether any reachable workflow still allows the exploit path to execute.