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Vulnerability · Published Apr 21, 2020 · Assigned by GitHub_M

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

Medium 6.5

In plain English

A medium-severity security flaw in Saml2 from Sustainsys. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 65% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)1.1%top 34.6% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
NuGetsustainsys.saml21.0.2GHSA-9475-xg6m-j7pw
NuGetsustainsys.saml22.7.0GHSA-9475-xg6m-j7pw

Affected products (as reported)

VendorProductVersions
Sustainsys Saml2 < 1.0.2>= 2.0.0, <= 2.6.0

Weakness: CWE-303 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:L/A:N

References