CVE-2023-23397
Published: March 14, 2023
Official Description
Microsoft Office Outlook contains a privilege escalation vulnerability that allows for a NTLM Relay attack against another service to authenticate as the user.
CISA KEV Advisory
Microsoft Office Outlook Privilege Escalation Vulnerability
Microsoft Office Outlook contains a privilege escalation vulnerability that allows for a NTLM Relay attack against another service to authenticate as the user.
Apply updates per vendor instructions.
Risk Analysis
Microsoft Office Outlook contains a privilege escalation vulnerability that enables an NTLM Relay attack against another service, allowing an attacker to authenticate as the user. The high EPSS score of 0.93658 indicates a significant likelihood of exploitation, requiring immediate attention. This vulnerability is also confirmed to be actively exploited, as it is in the KEV.
This vulnerability is actively being exploited in the wild. The flaw can be leveraged remotely to escalate privileges through NTLM Relay attacks.
Apply available security updates for Microsoft Office Outlook. Implement NTLM relay attack mitigations, such as Extended Protection for Authentication (EPA) and SMB signing.
Technical Analysis
CVE-2023-23397 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2023-23397 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
All References (2)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2023-23397 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1