CVE-2013-2551 is an use-after-free vulnerability in Microsoft Internet Explorer. CISA added it to the Known Exploited Vulnerabilities catalogue on 28 March 2022, which means attackers have used it in real attacks. Use-after-free vulnerability in Microsoft Internet Explorer allows remote attackers to execute remote code via a crafted web site that triggers access to a deleted object.
What Makes This Vulnerability Dangerous
Use-after-free flaws are memory-safety bugs, which means the browser can keep using an object after it has already been released. In Internet Explorer, that kind of bug is especially serious because a malicious page can shape browser state, trigger the stale reference, and turn a rendering error into code execution.
The core danger is that the attacker does not need a local foothold. A crafted website can deliver the exploit path remotely, so exposure often comes from ordinary web browsing rather than from installed software alone. For the underlying weakness pattern, see the broader memory-safety context in CWE Top 25 Guide.
How Organisations Check Exposure
Exposure review starts with knowing where the affected browser exists, which endpoints still run it, and whether those systems are permitted to reach untrusted web content. Because this is a publicly exploited CVE, organisations should treat asset inventory and internet-facing exposure as urgent questions rather than theoretical ones.
Authoritative CVE records are the right place to confirm the identifier and reference links, while vendor advisories and vulnerability tracking help determine whether the vulnerable product is still present in your environment. The official references are the CVE Program and the NIST National Vulnerability Database.
Remediation and Compensating Controls
When a patch cannot be applied immediately, the practical focus is to reduce exploitability: limit access to risky websites, reduce browser use on sensitive systems, and apply web filtering or segmentation where feasible. Temporary controls do not fix the bug, but they can lower the chance that a user session reaches the exploit trigger.
For vulnerabilities that are already known to be exploited in the wild, remediation should be prioritised through a vulnerability management process that considers asset criticality, internet exposure, and business impact. Vulnerability Management Guide is a useful reference point for that prioritisation logic.
Detection and Post-Compromise Review
After exploitation, the main question is whether the browser session or endpoint was used to establish persistence, run code, or pivot further. Even when the initial trigger is a web page, the practical consequence is endpoint compromise, so defenders should review browser telemetry, process launches, and any unusual child processes associated with the affected machine.
Post-patch review should also check for secondary changes made during the compromise window, especially if the system had access to credentials, browser sessions, or internal resources. If exploit activity is suspected, treat the endpoint as potentially hostile until the review shows otherwise. A broader exploitation and incident context is covered in The State of NHI & AI Agent Breach Report 2026.
Risk and Threat Considerations
Because this flaw is remotely triggerable from a crafted website and has been used in real attacks, the main risk is not just browser instability, but remote code execution on systems that trust normal web traffic. That makes it a direct foothold risk for endpoint compromise and, in some environments, a path into internal networks.
Failure mechanism: The attacker induces Internet Explorer to access a freed object, corrupting memory in a way that can redirect execution flow and run attacker-controlled code.
Impact: Successful exploitation can compromise the endpoint, expose data and sessions on that machine, and create a launch point for broader intrusion activity.
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 and OWASP ASVS set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| MITRE ATT&CK | T1189 — Drive-by Compromise | A malicious website can deliver the exploit through normal browsing. |
| Recommendation — Hunt for drive-by delivery patterns and correlate browser-triggered execution with suspicious child processes. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | This CVE requires asset awareness, prioritisation, and remediation tracking. |
| Recommendation — Prioritise exposed endpoints, verify remediation status, and track exception handling until exposure is removed. | ||
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | Known exploited browser flaws require timely identification and remediation. |
| Recommendation — Patch or mitigate the vulnerable browser environment as soon as feasible and verify the fix. | ||
| OWASP ASVS | V15 — Secure Coding and Architecture | Use-after-free is a memory-safety weakness class relevant to secure software design. |
| V16 — Security Logging and Error Handling | Post-exploitation review depends on visibility into suspicious browser behavior. | |
| Recommendation — Review memory-ownership assumptions and eliminate stale-reference patterns in code paths that process untrusted input. Retain sufficient telemetry to investigate exploit attempts and post-compromise activity. | ||
Practitioner Guidance
Why practitioners should care: Treat the CVE as a live exposure, not a historical browser bug. The combination of remote delivery and real-world exploitation means exposed systems can be compromised simply by user interaction with malicious content.
What to watch for: Prioritise any endpoint that still allows the vulnerable browser path, especially if it handles untrusted browsing, has elevated user rights, or stores credentials and authenticated sessions that would be valuable after compromise.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on October 17, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org