CVE-2023-36893
Published: 08 August 2023
Summary
CVE-2023-36893 is a medium-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Outlook. Its CVSS base score is 6.5 (Medium).
Operationally, ranked in the top 23.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Deeper analysis
Microsoft Outlook contains a spoofing vulnerability tracked as CVE-2023-36893 that affects the client’s handling of incoming messages. The flaw received a CVSS 3.1 score of 6.5 with network attack vector, low complexity, no required privileges, and user-interaction requirements, resulting in high confidentiality impact while leaving integrity and availability untouched.
An unauthenticated remote attacker can deliver a specially crafted message that, once opened or previewed by the recipient, allows spoofed content to be presented, potentially exposing sensitive information from the victim’s mailbox or connected services. Exploitation therefore requires the target user to interact with the malicious message but does not need prior authentication or elevated privileges on the attacker’s part.
The Microsoft Security Response Center advisory at the referenced URL supplies the official patch and mitigation guidance. EPSS for the CVE rose from a low baseline to a peak of 0.0741 on 2025-01-22 before receding to the current value of 0.0092, indicating a period of increased exploitation interest after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-40813
Vulnerability details
Microsoft Outlook 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.
Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Directly implements checks on information inputs to reject invalid data before processing.
Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.