#VU46500 Input validation error in ASP.NET Core MVC - CVE-2020-1045

Vulnerability identifier: #VU46500

Vulnerability risk: Medium

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-1045

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ASP.NET Core MVC
Universal components / Libraries / Software for developers

Vendor: Microsoft

Description

The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists due to insufficient validation of 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.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

ASP.NET Core MVC: 2.1.0 - 3.1

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External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1045

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.