CVE-2023-41890: Sustainsys.Saml2 library adds SAML2P support to ASP.NET web sites, allowing the web site to act as a SAML2 Service Provider. Prior to versions 1.0.3 ...

Description

Sustainsys.Saml2 library adds SAML2P support to ASP.NET web sites, allowing the web site to act as a SAML2 Service Provider. Prior to versions 1.0.3 and 2.9.2, when a response is processed, the issuer of the Identity Provider is not sufficiently validated. This could allow a malicious identity provider to craft a Saml2 response that is processed as if issued by another identity provider. It is also possible for a malicious end user to cause stored state intended for one identity provider to be used when processing the response from another provider. An application is impacted if they rely on any of these features in their authentication/authorization logic: the issuer of the generated identity and claims; or items in the stored request state (AuthenticationProperties). This issue is patched in versions 2.9.2 and 1.0.3. The `AcsCommandResultCreated` notification can be used to add the validation required if an upgrade to patched packages is not possible.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.60%

44.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Sustainsys	Saml2	< 1.0.3
Sustainsys	Saml2	>= 2.0.0, < 2.9.2

References

https://github.com/Sustainsys/Saml2/issues/712Issue Tracking, Patch
https://github.com/Sustainsys/Saml2/issues/713Issue Tracking, Patch
https://github.com/Sustainsys/Saml2/security/advisories/GHSA-fv2h-753j-9g39Third Party Advisory
https://github.com/Sustainsys/Saml2/issues/712Issue Tracking, Patch
https://github.com/Sustainsys/Saml2/issues/713Issue Tracking, Patch
https://github.com/Sustainsys/Saml2/security/advisories/GHSA-fv2h-753j-9g39Third Party Advisory

Timeline

Published: Sep 19, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-41890?

Sustainsys.Saml2 library adds SAML2P support to ASP.NET web sites, allowing the web site to act as a SAML2 Service Provider. Prior to versions 1.0.3 and 2.9.2, when a response is processed, the issuer of the Identity Provider is not sufficiently validated. This could allow a malicious identity provider to craft a Saml2 response that is processed as if issued by another identity provider. It is also possible for a malicious end user to cause stored state intended for one identity provider to be used when processing the response from another provider. An application is impacted if they rely on any of these features in their authentication/authorization logic: the issuer of the generated identity and claims; or items in the stored request state (AuthenticationProperties). This issue is patched in versions 2.9.2 and 1.0.3. The `AcsCommandResultCreated` notification can be used to add the validation required if an upgrade to patched packages is not possible.

How severe is CVE-2023-41890?

CVE-2023-41890 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.60% probability of exploitation in the next 30 days.

How do I fix CVE-2023-41890?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.