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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTk0NzUteGc2bS1qN3B3

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

Impact

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 tocken to create a log in session.

Patches

Version 1.0.2 and 2.7.0 are patched.

Workarounds

Ensure that any IdentityProvider trusted by the Sustainsys.Saml2 SP only issues bearer tokens if the audience matches the Sustainsys.Saml2 SP.

For more information

If you have any questions or comments about this advisory:

Permalink: https://github.com/advisories/GHSA-9475-xg6m-j7pw
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTk0NzUteGc2bS1qN3B3
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: about 4 years ago
Updated: over 1 year ago


CVSS Score: 6.5
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N

Identifiers: GHSA-9475-xg6m-j7pw, CVE-2020-5268
References: Repository: https://github.com/Sustainsys/Saml2
Blast Radius: 1.0

Affected Packages

nuget:Sustainsys.Saml2
Dependent packages: 0
Dependent repositories: 0
Downloads: 6,516,467 total
Affected Version Ranges: >= 2.0.0, < 2.7.0, < 1.0.2
Fixed in: 2.7.0, 1.0.2
All affected versions: 0.23.0, 0.24.0, 1.0.0, 1.0.1, 2.0.0, 2.1.0, 2.2.0, 2.3.0, 2.4.0, 2.5.0, 2.6.0
All unaffected versions: 1.0.2, 1.0.3, 2.7.0, 2.8.0, 2.9.0, 2.9.1, 2.9.2