CVE-2020-5268CWE-303

Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET

Medium · published April 21, 2020

CVSS v3.1
6.5
EPSS
1%
Percentile
65.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.01086 · 65.0th percentile
Weakness
CWE-303 · Incorrect Implementation of Authentication Algorithm
Published
2020-04-21T15:30Z
EPSS history
Timeline
  • 21 APR 15:30Z
    Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET
    cvelistv5