AIKIDO-2026-10856
AspNetSaml is vulnerable to Authentication Bypass
81
High Risk
This Affects:
AspNetSamlTL;DR
AspNetSaml validates SAML response signatures and expiration but does not verify the assertion audience against the service provider EntityID. An assertion issued for one service provider can be reused against another application that trusts the same identity provider. This can let an authenticated user gain access to the wrong service provider with a valid but mis-scoped assertion. The fix adds IsValid(string audienceEntityId) and rejects responses whose AudienceRestriction does not contain the expected SP EntityID.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range.
Background info
AspNetSaml is vulnerable to Authentication Bypass in versions 1.2.0 - 2.1.5.
How to fix this
Upgrade the AspNetSaml library to the patch version.
Are You Affected?
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SOC 2Compliant
ISO 27001Compliant