Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-23397 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Outlook. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Protocol or Service Impersonation (T1001.003); ranked in the top 0.1% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
Microsoft Outlook contains an elevation of privilege vulnerability identified as CVE-2023-23397. The flaw carries a CVSS v3.1 score of 9.8 and is associated with CWE-20 and CWE-294, indicating issues with improper input validation and authentication. It affects the Outlook email client and permits unauthenticated network-based attacks that require no user interaction.
An attacker can send a specially crafted message that triggers the vulnerability, allowing full elevation of privileges on the target system and resulting in complete loss of confidentiality, integrity, and availability.
Microsoft has issued remediation guidance through its Security Response Center, directing administrators to apply the available security updates. The vulnerability is listed in CISA’s catalog of known exploited vulnerabilities, confirming observed exploitation activity.
The associated EPSS score remains at a high level, with a recorded peak of 0.9575 and a current value of 0.9340.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-27497
Vulnerability Data
Microsoft Outlook Elevation of Privilege Vulnerability
- CWE(s)
- KEV Date Added
- 14 March 2023
Related Threats
Threat-Actor AttributionAI
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V10.4.16V10.5.1
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.
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.
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.
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.
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.
Strong authentication methods can reduce replay risk but do not inherently address captured messages.
Protecting and verifying identity assertions prevents replay of captured authentication material.
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.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-20, a class-level weakness, and none of its children carries one either.