CVE-2020-5268

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account, but needs a user to act. High risk of data exposure.

Exploit odds

1.1% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-04-21 17:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:21 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.1% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-04-21 17:15 UTC

Last modified

2026-06-17 03:21 UTC

Exploit probability

1.1% · EPSS, next 30 days

Weakness

CWE-303

Record status

Modified

Affected

• Sustainsys saml2 < 1.0.2
• Sustainsys saml2 < 2.7.0

Attack profile CVSS 3.1 · 6.5

Attack vector

Network

Complexity

High

Privileges needed

Low

User interaction

Required

Scope

Changed

Confidentiality

High

Integrity

Low

Availability

None

Is it in your code?

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