Microsoft Internet Explorer iepeers.dll Use-After-Free Remote Code Execution Vulnerability (CVE-2010-0806)

1. Official Security Patch

Apply the cumulative security update for Internet Explorer (MS10-018 or later) to update the iepeers.dll library.

2. Temporary Mitigations

If patching is not immediately feasible in legacy environments, apply the following workarounds:

A. Set the ActiveX Kill-Bit for iepeers.dll CLSID

Prevent Internet Explorer from loading the vulnerable component by configuring the registry compatibility flags:

reg add "HKLM\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{181B4CC0-ECE0-11D1-B901-00A0C90815EE}" /v "Compatibility Flags" /t REG_DWORD /d 0x00000400 /f
reg add "HKLM\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\ActiveX Compatibility\{181B4CC0-ECE0-11D1-B901-00A0C90815EE}" /v "Compatibility Flags" /t REG_DWORD /d 0x00000400 /f

B. Restrict Access to iepeers.dll

Disable read and execute permissions on the physical DLL file to prevent it from being loaded by the system:

cacls %SystemRoot%\System32\iepeers.dll /E /P everyone:N

This vulnerability is a Use-After-Free (UAF) flaw residing within the Peer Objects component (iepeers.dll) of Microsoft Internet Explorer.

An attacker can exploit this vulnerability by constructing a malicious web page that instantiates a specific object, deletes it to free its allocated memory, and subsequently references the resulting dangling pointer. By manipulating the heap layout (heap spraying), the attacker can populate the freed memory space with malicious shellcode, leading to arbitrary code execution within the context of the browser process.

This vulnerability was actively exploited in the wild in March 2010. Due to its high reliability and historical significance, it is listed in the CISA KEV catalog and maintains an extremely high EPSS score of 0.94.