# CVE-2018-8126: Internet Explorer Security Feature Bypass Vulnerability

CVE-2018-8126 is fixed in 11 products on 1 platform, first by KB4103723, released May 8, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2018-8126
- Priority: Routine
- CVSS: 5.3 (Important)
- EPSS: 0.0550
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: May 8, 2018
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2018-8126

## Description

<p>A security feature bypass vulnerability exists when Internet Explorer fails to validate User Mode Code Integrity (UMCI) policies. The vulnerability could allow an attacker to bypass Device Guard UMCI policies.</p> <p>To exploit the vulnerability, a user could either visit a malicious website or an attacker with access to the system could run a specially crafted application. An attacker could then leverage the vulnerability to run unsigned malicious code as though it were signed by a trusted source.</p> <p>The update addresses the vulnerability by correcting how Internet Explorer validates UMCI policies.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Internet Explorer 11 on Windows 10 Version 1607 for 32-bit Systems | 14393.2248 | [KB4103723](https://patchblox.com/security/data/fix/microsoft/kb4103723.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1607 for x64-based Systems | 14393.2248 | [KB4103723](https://patchblox.com/security/data/fix/microsoft/kb4103723.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1703 for 32-bit Systems | 15063.1088 | [KB4103731](https://patchblox.com/security/data/fix/microsoft/kb4103731.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1703 for x64-based Systems | 15063.1088 | [KB4103731](https://patchblox.com/security/data/fix/microsoft/kb4103731.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1709 for 32-bit Systems | 16299.431 | [KB4103727](https://patchblox.com/security/data/fix/microsoft/kb4103727.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1709 for x64-based Systems | 16299.431 | [KB4103727](https://patchblox.com/security/data/fix/microsoft/kb4103727.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1803 for 32-bit Systems | 17134.48 | [KB4103721](https://patchblox.com/security/data/fix/microsoft/kb4103721.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 Version 1803 for x64-based Systems | 17134.48 | [KB4103721](https://patchblox.com/security/data/fix/microsoft/kb4103721.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 for 32-bit Systems | 10240.17861 | [KB4103716](https://patchblox.com/security/data/fix/microsoft/kb4103716.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows 10 for x64-based Systems | 10240.17861 | [KB4103716](https://patchblox.com/security/data/fix/microsoft/kb4103716.md) | May 8, 2018 |
| Microsoft | Internet Explorer 11 on Windows Server 2016 | 14393.2248 | [KB4103723](https://patchblox.com/security/data/fix/microsoft/kb4103723.md) | May 8, 2018 |

---

Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.