CVE-2026-21665
Published: 23 February 2026
Summary
CVE-2026-21665 is a high-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Microsoft (inferred from references). Its CVSS base score is 7.7 (High).
Operationally, ranked in the top 35.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7470
Vulnerability details
The Print Service component of Fiserv Originate Loans Peripherals (formerly Velocity Services) in unsupported version 2021.2.4 (build 4.7.3155.0011) uses deprecated .NET Remoting TCP channels that allow unsafe deserialization of untrusted data. When these services are exposed to an untrusted network…
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in a client-managed deployment, an unauthenticated attacker can achieve remote code execution. Version 2021.2.4 is no longer supported by Fiserv. Customers should upgrade to a currently supported release (2025.1 or later) and ensure that .NET Remoting service ports are not exposed beyond trusted network boundaries. This CVE documents behavior observed in a client-hosted deployment running an unsupported legacy version of Originate Loans Peripherals with .NET Remoting ports exposed to an untrusted network. This is not a default or supported configuration. Customers running legacy versions should upgrade to a currently supported release and ensure .NET Remoting ports are restricted to trusted network segments. The finding does not apply to Fiserv-hosted environments.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
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.
Penetration testing supplies malicious serialized objects, detecting unsafe deserialization and supporting corrective actions.
Evaluation of untrusted data handling (deserialization testing) reveals unsafe processing, which the required remediation process addresses.
Untrusted serialized data can be deserialized and observed inside the chamber, blocking gadget-chain exploitation outside the sandbox.
Validates or rejects untrusted serialized data before deserialization occurs.
Identifies and blocks malicious code introduced through deserialization of untrusted data at system boundaries.
Integrity verification of serialized information can detect tampering before deserialization occurs.
Provenance of associated data allows detection of untrusted sources before deserialization or processing occurs.