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TI-2023-22282 Aliases CVE-2023-41890GHSA-fv2h-753j-9g39

Sustainsys.Saml2 Insufficient Identity Provider Issuer Validation

Priority MEDIUM 40CWE-289Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-294.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00752 55th percentileScored 2026-11-07
Fix Fixed Saml2 (Sustainsys): 1.0.3, 2.9.2Sustainsys.Saml2 (NuGet): 1.0.3, 2.9.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
SustainsysSaml2before 1.0.3; 2.0.0 to before 2.9.21.0.3, 2.9.2Patch availableCNA
—Sustainsys.Saml2 (NuGet)before 1.0.31.0.3Patch availableGHSA-fv2h-753j-9g39
—Sustainsys.Saml2 (NuGet)2.0.0 to before 2.9.22.9.2Patch availableGHSA-fv2h-753j-9g39
—Kentor.AuthServices (NuGet)up to 0.23.0—No fix listedGHSA-fv2h-753j-9g39
  • Saml2 VendorSustainsys Affected before 1.0.3; 2.0.0 to before 2.9.2 Fixed in 1.0.3, 2.9.2 Patch available CNA
  • Sustainsys.Saml2 (NuGet) Vendor— Affected before 1.0.3 Fixed in 1.0.3 Patch available GHSA-fv2h-753j-9g39
  • Sustainsys.Saml2 (NuGet) Vendor— Affected 2.0.0 to before 2.9.2 Fixed in 2.9.2 Patch available GHSA-fv2h-753j-9g39
  • Kentor.AuthServices (NuGet) Vendor— Affected up to 0.23.0 Fixed in — No fix listed GHSA-fv2h-753j-9g39

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:sustainsys:saml2:*:*:*:*:*:*:*:*before 1.0.3; 2.0.0 to before 2.9.2VulnerableSustainsys
  • cpe:2.3:a:sustainsys:saml2:*:*:*:*:*:*:*:* Versions before 1.0.3; 2.0.0 to before 2.9.2 Vulnerable ·Sustainsys

Remediation

  • Fix · CNA Saml2 (Sustainsys) Fixed in 1.0.3, 2.9.2
  • Fix · GHSA-fv2h-753j-9g39 Sustainsys.Saml2 (NuGet) Fixed in 1.0.3 Advisory →
  • Fix · GHSA-fv2h-753j-9g39 Sustainsys.Saml2 (NuGet) Fixed in 2.9.2 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-41890
  2. 2026-10-03 Alias added: GHSA-fv2h-753j-9g39

References

Patch 2

Advisory 2

Other 1

  • TI-2020-04317 Missing Token Replay Detection CVSS 3.1HIGH 8.2
  • TI-2020-04324 Subject Confirmation Method not validated in Saml2 Authentication Services for ASP.NET CVSS 3.1HIGH 7.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences