CVE-2020-5268 Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET

2020-04-2115:30:37

CWE-303

GitHub_M

www.cve.org

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

LOW

Availability Impact

NONE

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

0.001 Low

EPSS

Percentile

48.3%

JSON

In Saml2 Authentication Services for ASP.NET versions before 1.0.2, and between 2.0.0 and 2.6.0, there is a vulnerability in how tokens are validated in some cases. Saml2 tokens are usually used as bearer tokens - a caller that presents a token is assumed to be the subject of the token. There is also support in the Saml2 protocol for issuing tokens that is tied to a subject through other means, e.g. holder-of-key where possession of a private key must be proved. The Sustainsys.Saml2 library incorrectly treats all incoming tokens as bearer tokens, even though they have another subject confirmation method specified. This could be used by an attacker that could get access to Saml2 tokens with another subject confirmation method than bearer. The attacker could then use such a token to create a log in session. This vulnerability is patched in versions 1.0.2 and 2.7.0.

CNA Affected

[
  {
    "product": "Saml2",
    "vendor": "Sustainsys",
    "versions": [
      {
        "status": "affected",
        "version": "< 1.0.2"
      },
      {
        "status": "affected",
        "version": ">= 2.0.0, <= 2.6.0"
      }
    ]
  }
]