Is CVE-2015-2502 (Microsoft Internet Explorer Memory Corruption) being exploited in the wild?

Yes. CISA added CVE-2015-2502 to its Known Exploited Vulnerabilities catalogue on 13 April 2022, which it does only when there is reliable evidence of active exploitation. CISA has not linked it to known ransomware campaigns. Microsoft Internet Explorer contains a memory corruption vulnerability that allows an attacker to execute code or cause a denial-of-service (DoS).

What “exploited in the wild” means for this CVE

For a KEV-listed vulnerability, “exploited in the wild” means there is credible evidence that real attackers have used it against live systems, not just that the flaw is theoretically exploitable. That changes the question from “is this a patch candidate?” to “is this an active exposure that needs immediate triage, containment, and verification?”

CVE-2015-2502 is a memory corruption issue in Microsoft Internet Explorer, so the practical concern is code execution or denial of service through crafted content or browser interaction. Because the flaw sits in a widely used client application, exposure depends not only on whether the browser exists on a device, but also whether users still open untrusted content paths that can trigger the vulnerable code.

Attackers usually care about this class of flaw because browser memory corruption can provide a low-friction initial foothold. Once exploitation is possible, the next step is often to execute code in the user context, stage additional payloads, or chain into credential theft and broader endpoint compromise.

How to confirm exposure and reduce the attack window

The first decision is whether Internet Explorer is still present and reachable on any managed endpoint, kiosk, or legacy application workflow. If it is, treat those systems as exposed until you have verified the browser is not used for active browsing, embedded web content, or compatibility-driven business processes.

Use the vendor advisory and the CISA Known Exploited Vulnerabilities Catalog to confirm the required remediation path, then validate whether your asset inventory still shows IE-capable systems. The point is not just to patch the CVE, but to find where the vulnerable software remains reachable in practice.

Where patching or decommissioning is delayed, reduce exposure by removing user access to the browser where possible, hardening internet-facing browsing paths, and restricting access to untrusted content that could trigger the flaw. If the system cannot be upgraded quickly, isolate it operationally so a single browser compromise does not become a broader endpoint compromise.

What to check after remediation

Because CISA only places entries in KEV when it has reliable evidence of active exploitation, you should assume there may already have been attempts against exposed systems. After remediation, review endpoint telemetry, browser logs, process creation, downloads, and suspicious child processes to look for post-exploitation activity around the relevant time window.

If there is any sign the browser was abused, investigate adjacent identity and session exposure as well. Browser exploitation often matters because it can lead to stolen cookies, cached credentials, saved passwords, or authenticated sessions, which means the impact may persist even after the vulnerable software is removed.

Also verify whether compensating controls worked as intended. If application allowlisting, browser hardening, or endpoint detection was supposed to block exploitation, check whether the attempted execution was prevented, alerted on, or allowed to proceed silently.

Risk and Threat Considerations

Browser memory corruption is attractive to attackers because it can turn a routine web interaction into code execution on a user endpoint. Once a KEV-listed browser flaw is being exploited, the main risk is not the CVE itself but the follow-on access it can provide into user sessions, downloaded content, and internal resources.

Failure mechanism: A crafted page, file, or embedded content path triggers corruption in browser memory handling, allowing attacker-controlled execution or a crash that can be chained into further compromise.

Impact: The likely outcomes are endpoint compromise, session theft, malware delivery, or denial of service, with greater blast radius on legacy systems that still depend on Internet Explorer for routine access.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

MITRE ATT&CK addresses the attack and risk surface, while CIS Controls v8, NIST SP 800-53 Rev 5, OWASP ASVS and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.

Framework	Control / Reference	Relevance
CIS Controls v8	CIS-7 — Continuous Vulnerability Management	KEV-listed exploitation requires prioritized vulnerability handling and exposure reduction.
	CIS-10 — Malware Defenses	Browser exploitation often leads to payload delivery and endpoint compromise attempts.
	CIS-18 — Penetration Testing	Verification after remediation should confirm exploitability and residual exposure paths are closed.
Recommendation — Prioritise and remediate the vulnerable browser asset based on active exploitation evidence. Harden endpoint defenses to detect and block post-exploitation activity from compromised browsers. Validate that the browser attack path is no longer exploitable on exposed systems.
NIST SP 800-53 Rev 5	SI-2 — Flaw Remediation	A known exploited browser flaw requires timely remediation and exposure tracking.
	SI-4 — System Monitoring	Post-remediation review needs monitoring for exploitation, payloads, and suspicious browser activity.
	CM-7 — Least Functionality	Reducing browser surface and legacy use lowers the practical attack window.
Recommendation — Patch or mitigate the vulnerable browser promptly and confirm completion across assets. Monitor for exploit indicators and follow-on compromise around the affected endpoints. Disable or restrict unnecessary browser functionality and legacy exposure paths.
OWASP ASVS	V16 — Security Logging and Error Handling	Investigation depends on logs that reveal exploit attempts and post-exploitation activity.
Recommendation — Retain and review logs that can confirm exploitation attempts and aftermath.
MITRE ATT&CK	T1203 — Exploitation for Client Execution	A browser memory corruption exploit is a classic client-execution attack path.
	T1059 — Command and Scripting Interpreter	Successful browser exploitation often leads to script or command execution after initial code run.
Recommendation — Hunt for client-side exploitation patterns that delivered code execution through the browser. Look for subsequent command execution that followed the browser compromise.
NIST CSF 2.0	RC.RP-01 — Recovery Plan Execution	Known exploitation warrants a recovery-oriented response and validation of restored state.
Recommendation — Execute recovery steps and verify the system is clean before returning it to normal use.

Practitioner Guidance

What to prioritise: Focus first on exposed endpoints that still run Internet Explorer for business reasons, especially where users have access to untrusted web content or legacy intranet applications. Those systems carry the highest practical risk even if they are not your most modern assets.

What to verify: Confirm remediation by checking both software state and usage state, because an installed browser that nobody uses is a very different risk from an installed browser that remains reachable through shortcuts, embedded controls, or legacy workflows. Validate that browser-hardening controls and endpoint detections are actually producing evidence.

Decision rule: If you cannot remove or patch the exposure immediately, treat the system as a temporary high-risk exception and narrow its browsing surface, network reach, and user access until the vulnerable path is gone.

Practitioner takeaway: A KEV listing means you should assume active attacker interest already exists; the real job is to eliminate the reachable attack path and then check whether compromise or session exposure occurred before remediation.