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

Medium 5.5 Published 21 May 2020 Updated 19 Aug 2026

An unauthenticated attacker can execute scripts in the victim's browser context via XSS in ADFS, potentially compromising user sessions.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2020-1055?

CVE-2020-1055 is a medium-severity cross-site scripting vulnerability in Microsoft Windows 10, published on 21 May 2020. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-79

Which versions are affected by CVE-2020-1055?

It affects 3 products.

Products include Microsoft Windows 10, Microsoft Windows Server 2016, Microsoft Windows Server 2019.

How do I fix CVE-2020-1055?

No fix has been published for CVE-2020-1055 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2020-1055 being exploited?

There is no known exploitation of CVE-2020-1055 in the wild and no public exploit code.

All Microsoft Windows 10 vulnerabilities

Sources

Also known as GHSA-xqf6-p37p-9cxg.