CVE-2020-1045: Microsoft ASP.NET Core Security Feature Bypass Vulnerability
<p>A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.</p> <p>The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker to set a second cookie with the name being percent encoded.</p> <p>The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names.</p>
Other sources
A security feature bypass vulnerability exists in the way Microsoft ASP.NET Core parses encoded cookie names.The ASP.NET Core cookie parser decodes entire cookie strings which could allow a malicious attacker to set a second cookie with the name being percent encoded.The security update addresses the vulnerability by fixing the way the ASP.NET Core cookie parser handles encoded names., aka 'Microsoft ASP.NET Core Security Feature Bypass Vulnerability'.
It was discovered that ASP.NET did not properly decode certain cookie values. A remote attacker could exploit this to bypass the "Cookie Prefixes" security mechanism by sending specially crafted cookies to a vulnerable web application.
— Red Hat
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2020-1045?
CVE-2020-1045 is a security feature bypass vulnerability in Microsoft ASP.NET Core.
What is the severity of CVE-2020-1045?
The severity of CVE-2020-1045 is high (7.5).
Which software is affected by CVE-2020-1045?
Microsoft ASP.NET Core versions 2.1.21 to 2.1 and 3.1.8 to 3.1 are affected by CVE-2020-1045.
How does CVE-2020-1045 work?
CVE-2020-1045 allows a malicious attacker to set a second cookie with a percent-encoded name by exploiting how ASP.NET Core parses encoded cookie names.
How can I fix CVE-2020-1045?
Update to the patched versions of Microsoft ASP.NET Core (2.1.21 or later for 2.1.x versions, 3.1.8 or later for 3.1.x versions).