How severe is CVE-2023-23397?

CVE-2023-23397 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-23397 being actively exploited?

Yes. CVE-2023-23397 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-03-14, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2023-23397?

CVE-2023-23397 primarily affects Microsoft 365 Apps. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-23397?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2023-23397 have an EU (EUVD) identifier?

Yes. CVE-2023-23397 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-27497. It is also flagged as exploited in the EUVD (since 2023-03-14).

When was CVE-2023-23397 published?

CVE-2023-23397 was published on 2023-03-14 and last updated on 2026-06-17.

CVE-2023-23397

CVE-2023-23397 is a critical-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 9.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2023-03-14). The underlying weakness is classified as CWE-294.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 97% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2023-03-14)
EU (EUVD) id: EUVD-2023-27497
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2023-03-14)
Weakness: CWE-294
Affected product: Microsoft 365 Apps
Published: 2023-03-14
Last modified: 2026-06-17

Description

Microsoft Outlook Elevation of Privilege Vulnerability

Frequently asked questions

What is CVE-2023-23397?: Microsoft Outlook Elevation of Privilege Vulnerability
How severe is CVE-2023-23397?: CVE-2023-23397 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-23397 being actively exploited?: Yes. CVE-2023-23397 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-03-14, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2023-23397?: CVE-2023-23397 primarily affects Microsoft 365 Apps. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-23397?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2023-23397 have an EU (EUVD) identifier?: Yes. CVE-2023-23397 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-27497. It is also flagged as exploited in the EUVD (since 2023-03-14).
When was CVE-2023-23397 published?: CVE-2023-23397 was published on 2023-03-14 and last updated on 2026-06-17.

References

Affected products (6)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:outlook:2013:sp1:*:*:-:*:*:*
cpe:2.3:a:microsoft:outlook:2013:sp1:*:*:rt:*:*:*
cpe:2.3:a:microsoft:outlook:2016:*:*:*:*:*:*:*

More vulnerabilities in Microsoft 365 Apps

CVE-2026-78509 — Critical (CVSS 9.8): Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
CVE-2024-21413 — Critical (CVSS 9.8): Microsoft Outlook Remote Code Execution Vulnerability
CVE-2020-0901 — Critical (CVSS 9.8): A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle…
CVE-2023-33150 — Critical (CVSS 9.6): Microsoft Office Security Feature Bypass Vulnerability
CVE-2026-70125 — High (CVSS 8.8): Microsoft Office Outlook Remote Code Execution Vulnerability
CVE-2026-81952 — High (CVSS 8.8): Heap-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code over a network.

All CVEs affecting Microsoft 365 Apps →

Other CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities

CVE-2025-49752 — Critical (CVSS 10.0): Azure Bastion Elevation of Privilege Vulnerability
CVE-2026-88278 — Critical (CVSS 9.8): GeoVision GV-LPC2211 V1.13 fails to enforce WS-Security UsernameToken freshness or nonce reuse protection, allowing a…
CVE-2026-86219 — Critical (CVSS 9.8): Authen::SASL::Perl::DIGEST_MD5 versions before 2.2100 for Perl accept replayed authentication responses via unverified…
CVE-2026-65905 — Critical (CVSS 9.8): Authentication Bypass by Capture-replay vulnerability in Apache Tomcat's DIGEST authenticator. If, before windowSize…
CVE-2026-68079 — Critical (CVSS 9.8): In Apache CXF's DefaultEncryptingCodeDataProvider, a captured authorization code can be redeemed an unlimited number…
CVE-2026-28564 — Critical (CVSS 9.8): Insufficient Session Expiration, Authentication Bypass by Capture-replay vulnerability in Apache IoTDB. REST Basic…

Browse all CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities →