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

高 7.3CVE-2020-5268 · GHSA-9475-xg6m-j7pw · 21/04/2020 公開 · 17/06/2026 更新

要点

CVE-2020-5268 は Sustainsys.Saml2, saml2 (sustainsys) に影響する深刻度「高」 (CVSS 7.3) の脆弱性です。
今後30日間に悪用される確率（EPSS）：1.1%（全脆弱性の 65.4% より高い）。
対処：2.7.0, 1.0.2 以降に更新してください。

パッケージ	影響を受けるバージョン	修正済みバージョン
Sustainsys.Saml2 NuGet	`≥ 2.0.0, < 2.7.0< 1.0.2`	`2.7.01.0.2`
saml2 sustainsys	`≥ 2.0.0, < 2.7.0< 1.0.2`	`2.7.01.0.2`

概要

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:

Comment on #103
Email us at [email protected] if you think that there are further security issues.

NVD の説明

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.