# CVE-2020-1055: Microsoft Active Directory Federation Services Cross-Site Scripting Vulnerability

CVE-2020-1055 is fixed in 13 products on 1 platform, first by KB4551853, released May 12, 2020. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2020-1055
- Priority: High
- CVSS: n/a (Important)
- EPSS: 0.0245
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: May 12, 2020
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-1055

## Description

<p>A cross-site-scripting (XSS) vulnerability exists when Active Directory Federation Services (ADFS) does not properly sanitize user inputs. An un-authenticated attacker could exploit the vulnerability by sending a specially crafted request to an affected ADFS server.</p> <p>The attacker who successfully exploited the vulnerability could then perform cross-site scripting attacks on affected systems and run scripts in the security context of the current user.</p> <p>This security update addresses the vulnerability by ensuring that ADFS properly sanitizes user inputs.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Windows 10 Version 1809 for 32-bit Systems | 17763.1217 | [KB4551853](https://patchblox.com/security/data/fix/microsoft/kb4551853.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1809 for ARM64-based Systems | 17763.1217 | [KB4551853](https://patchblox.com/security/data/fix/microsoft/kb4551853.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1809 for x64-based Systems | 17763.1217 | [KB4551853](https://patchblox.com/security/data/fix/microsoft/kb4551853.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1903 for 32-bit Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1903 for ARM64-based Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1903 for x64-based Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1909 for 32-bit Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1909 for ARM64-based Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows 10 Version 1909 for x64-based Systems |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows Server 2019 | 17763.1217 | [KB4551853](https://patchblox.com/security/data/fix/microsoft/kb4551853.md) | May 12, 2020 |
| Microsoft | Windows Server 2019 (Server Core installation) | 17763.1217 | [KB4551853](https://patchblox.com/security/data/fix/microsoft/kb4551853.md) | May 12, 2020 |
| Microsoft | Windows Server, version 1903 (Server Core installation) |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |
| Microsoft | Windows Server, version 1909 (Server Core installation) |  | [KB4556799](https://patchblox.com/security/data/fix/microsoft/kb4556799.md) | May 12, 2020 |

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Data as of 2026-11-08T00:53:09Z 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

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