CVE-2013-2551

This vulnerability is like a “memory bookkeeping” mistake in Internet Explorer. When you open a malicious, specially crafted web page, it can trick the browser into using an already-deleted piece of memory, which can let an attacker run code on your computer—potentially installing malware.

This matters if your business still runs Microsoft Internet Explorer 6 through 10 on any workstation or server used for web browsing. It’s typically only a risk when a user can be exposed to a malicious website (the attacker needs you to visit the crafted page in the vulnerable browser). CISA’s KEV entry also indicates it has been used in real ransomware campaigns.

This is urgent and should be treated as a high-priority emergency fix because it’s confirmed in the CISA KEV catalog and has been used in ransomware campaigns. If any of your machines still use Internet Explorer 6–10, attackers can target users through web browsing, so remediation must happen immediately.

Confirm exposure (quick)

1. Identify every endpoint where Internet Explorer 6, 7, 8, 9, or 10 is used.
   • Ask IT to check installed browser versions on workstations, kiosk machines, and any legacy apps that embed IE.
2. For each affected endpoint, verify whether the Microsoft remediation for MS13-037 is installed.
   • If MS13-037 is present, you’ve covered the vendor fix for this CVE; if not, treat the endpoint as still vulnerable.

Upgrade/remediate (target)

1. Primary recommendation: stop using Internet Explorer and switch users to a modern browser.
2. If Internet Explorer must remain for compatibility, apply the vendor updates per MS13-037 to the affected devices.
3. Re-check after patching that the update is actually installed (not just “downloaded” or “pending”).

Temporary workaround (if patching is delayed)

• Immediately restrict exposure by preventing users from browsing the public web with Internet Explorer (for example: policy-based blocking, removing IE from normal use, or controlling shortcuts).
• If you have to keep IE for a legacy application, isolate that use (separate user accounts, strict website access controls), and ensure MS13-037 is applied as soon as possible.

KEV deadline note

• CISA KEV remediation due date for this issue was 2022-04-18.

What to monitor

• Review proxy/web logs for access attempts that hit suspicious or newly registered domains.
• Check endpoint alerts for signs of browser exploitation and subsequent payload execution (new processes spawned by the browser, unexpected downloads, or unusual persistence changes).

CVE-2013-2551 is a use-after-free vulnerability (CWE-416) in Microsoft Internet Explorer 6 through 10. The trigger is a crafted website that causes Internet Explorer to access memory after the related object has been deleted, which can lead to remote code execution.

Exploitation status: CISA lists this CVE in the KEV catalog and it has been used in ransomware campaigns, so this should be treated as actively exploited rather than theoretical.

Patch guidance: Microsoft remediation is covered by MS13-037 (apply per Microsoft’s security bulletin instructions).

Exploit maturity: No public exploit code is noted in the findings, but the KEV entry indicates real-world attacker use.

EPSS note: A high predicted likelihood was reported, with a trend of falling; however, KEV-confirmed exploitation takes precedence for urgency.