CVE-2023-21762
Published: 10 January 2023
Summary
CVE-2023-21762 is a high-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Microsoft Exchange Server. Its CVSS base score is 8.0 (High).
Operationally, ranked in the top 39.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Deeper analysis
Microsoft Exchange Server is affected by CVE-2023-21762, a spoofing vulnerability assigned CWE-502 for deserialization of untrusted data. The flaw carries a CVSS 3.1 base score of 8.0 with an attack vector of adjacent network, low attack complexity, low privileges required, and no user interaction, resulting in high impact to confidentiality, integrity, and availability on an unchanged scope.
An attacker positioned on an adjacent network who already possesses low-privileged access can exploit the issue to perform spoofing actions that lead to full compromise of confidentiality, integrity, and availability on the targeted Exchange Server instance.
The listed references point to the Microsoft Security Response Center update guide for CVE-2023-21762, which practitioners should consult for official patch availability and mitigation guidance.
EPSS for this CVE rose materially from a low baseline to a peak of 0.0553 on 2025-01-22 before receding to the current value of 0.0039, indicating a period of increased exploitation interest after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-25929
Vulnerability details
Microsoft Exchange Server Spoofing Vulnerability
- 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.