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

Executive Summary

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. 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. This security update addresses the vulnerability by ensuring that ADFS properly sanitizes user inputs.

Overview

6.1

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Spoofing

Released May 12 2020

Last Updated May 12 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01784 — 0.76333 percentile

NVD CVSS 6.1 MEDIUM — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

SCOPE

Changed

EPSS Score

0.01784

probability of exploitation in the next 30 days

0.76333 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

13 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1809 for 32-bit Systems	`4551853 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4551853 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1809 for x64-based Systems	`4551853 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1903 for 32-bit Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1903 for x64-based Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1909 for 32-bit Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows 10 Version 1909 for x64-based Systems	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows Server 2019	`4551853 (Security Update)`	Important	Spoofing	Yes
Windows Server 2019 (Server Core installation)	`4551853 (Security Update)`	Important	Spoofing	Yes
Windows Server, version 1903 (Server Core installation)	`4556799 (Security Update)`	Important	Spoofing	Yes
Windows Server, version 1909 (Server Core installation)	`4556799 (Security Update)`	Important	Spoofing	Yes

Patches

2 patches

Article	Type	Restart
`4551853`	Security Update	Yes
`4556799`	Security Update	Yes

Exploits & PoC

No public exploit or PoC has been linked for this CVE yet. When available, references are sourced from public repositories and may be unverified or non-functional — review carefully before use.

Detection Rules

No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.

Acknowledgments

Steve Patches

References

MSRC Advisory MITRE NVD