Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-41890 is a high-severity Authentication Bypass by Alternate Name (CWE-289) vulnerability in Sustainsys Saml2. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 46% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-2496
Vulnerability Data
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…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 8 hardening rules · 3 OS baselines
V8.3.3V10.3.2V6.4.3V10.4.16
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Allows detection of capture-replay attacks by showing the replayed logon's timestamp as the last logon.
Protects against replay of captured session tokens or credentials by requiring authenticated, fresh session channels.
Wireless link protections commonly incorporate replay protection, reducing the exploitability of capture-replay weaknesses.
Accurate synchronized time enables tight timestamp windows that directly limit capture-replay windows in authentication protocols.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Network monitoring may detect anomalous replays after the fact but does not prevent the design flaw.
Proper identity management reduces alternate-name collisions but does not guarantee canonicalization inside the auth decision.
Strong authentication mechanisms directly prevent name-based bypass when they enforce canonical name checks.
Protecting and verifying identity assertions prevents replay of captured authentication material.
Authorization policy enforcement assumes correct identity; the weakness occurs before policy is applied.
Encryption and integrity protections for data-in-transit directly block capture-replay of credentials or tokens.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
A.5.15 only requires defining and documenting an access control policy plus requirements; it does not itself enforce rules or stop alternate-name authentication bypasses from being exploitable.
A.5.16 manages the lifecycle, uniqueness, and accountability of identities; it has no bearing on a product that authenticates by name but fails to canonicalize or check alternate names for the same resource/actor, so the weakness remains present and exploitable.
Proper management of authentication credentials can include rules against duplicate or alias identities.
A.5.18 governs the provisioning, review, and revocation of already-granted access rights to authenticated identities; it does not address or stop the distinct flaw in which authentication logic accepts an alternate name that bypasses the check.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248538 OL 8 operating systems booted with United Extensible Firmware Interface (UEFI) must have a unique name for the grub superusers account when booting into single-user mode and maintenance. blocks CWE-289
RHEL 7 (1 rule)
- V-244558 Red Hat Enterprise Linux operating systems version 7.2 or newer booted with United Extensible Firmware Interface (UEFI) must have a unique name for the grub superusers account when booting into single-user mode and maintenance. blocks CWE-289