How severe is CVE-2023-35311?

CVE-2023-35311 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-35311 being actively exploited?

Yes. CVE-2023-35311 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-07-11, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2023-35311?

CVE-2023-35311 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-2023-35311?

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-2023-35311 have an EU (EUVD) identifier?

Yes. CVE-2023-35311 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-39314. It is also flagged as exploited in the EUVD (since 2023-07-11).

When was CVE-2023-35311 published?

CVE-2023-35311 was published on 2023-07-11 and last updated on 2026-06-17.

CVE-2023-35311

CVE-2023-35311 is a high-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 8.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2023-07-11). The underlying weakness is classified as CWE-367.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 15% (96th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2023-07-11)
EU (EUVD) id: EUVD-2023-39314
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2023-07-11)
Weakness: CWE-367
Affected product: Microsoft 365 Apps
Published: 2023-07-11
Last modified: 2026-06-17

Description

Microsoft Outlook Security Feature Bypass Vulnerability

Frequently asked questions

What is CVE-2023-35311?: Microsoft Outlook Security Feature Bypass Vulnerability
How severe is CVE-2023-35311?: CVE-2023-35311 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-35311 being actively exploited?: Yes. CVE-2023-35311 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-07-11, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2023-35311?: CVE-2023-35311 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-2023-35311?: 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-2023-35311 have an EU (EUVD) identifier?: Yes. CVE-2023-35311 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-39314. It is also flagged as exploited in the EUVD (since 2023-07-11).
When was CVE-2023-35311 published?: CVE-2023-35311 was published on 2023-07-11 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:-:-:*:-:-:*:*
cpe:2.3:a:microsoft:outlook:2013:sp1:*:*:rt:*:*:*
cpe:2.3:a:microsoft:outlook:2016:*:*:*:*:*:*:*

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CVE-2024-21413 — Critical (CVSS 9.8): Microsoft Outlook Remote Code Execution Vulnerability
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