Security Resilience

CVE-2023-41890

Auth Bypass in Sustainsys Saml2 ≤ 1.0.3

Published
19 September 2023
Modified
21 November 2024
Patch / advisory
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0075 54th percentile
Risk Priority 59 floored blend · peak EPSS

CVSS 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

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

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-24027Shared CWE-294
CVE-2023-29158Shared CWE-294
CVE-2026-49319Shared CWE-294
CVE-2024-46041Shared CWE-294
CVE-2024-22066Shared CWE-294
CVE-2023-50128Shared CWE-294
CVE-2026-54148Shared CWE-294
CVE-2024-49595Shared CWE-294
CVE-2026-73312Shared CWE-294
CVE-2023-33281Shared CWE-294

Affected Assets

sustainsys
saml2
≤ 1.0.3 · 2.0.0 — 2.9.2

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 8 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V8.3.3
  • V10.3.2
  • V6.4.3
  • V10.4.16

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.

addresses: CWE-294

Allows detection of capture-replay attacks by showing the replayed logon's timestamp as the last logon.

addresses: CWE-294

Protects against replay of captured session tokens or credentials by requiring authenticated, fresh session channels.

addresses: CWE-294

Wireless link protections commonly incorporate replay protection, reducing the exploitability of capture-replay weaknesses.

addresses: CWE-294

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.

DE.CM-01 partial match
blocks

Network monitoring may detect anomalous replays after the fact but does not prevent the design flaw.

PR.AA-01 partial match
blocks

Proper identity management reduces alternate-name collisions but does not guarantee canonicalization inside the auth decision.

PR.AA-03 partial match
blocks

Strong authentication mechanisms directly prevent name-based bypass when they enforce canonical name checks.

PR.AA-04 partial match
blocks

Protecting and verifying identity assertions prevents replay of captured authentication material.

PR.AA-05 partial match
blocks

Authorization policy enforcement assumes correct identity; the weakness occurs before policy is applied.

PR.DS-02 partial match
blocks

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.

removes
blocks

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.

blocks

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.

degrades

Proper management of authentication credentials can include rules against duplicate or alias identities.

blocks

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.

removes

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

References