How severe is CVE-2026-64918?

CVE-2026-64918 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-64918 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-64918?

CVE-2026-64918 primarily affects Microsoft 365 Apps. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-64918?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-64918 published?

CVE-2026-64918 was published on 2026-09-08 and last updated on 2026-09-09.

CVE-2026-64918

CVE-2026-64918 is a medium-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-522.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-522
Affected product: Microsoft 365 Apps
Published: 2026-09-08
Last modified: 2026-09-09

Description

Insufficiently protected credentials in Microsoft Office allows an unauthorized attacker to perform spoofing over a network.

Frequently asked questions

What is CVE-2026-64918?: Insufficiently protected credentials in Microsoft Office allows an unauthorized attacker to perform spoofing over a network.
How severe is CVE-2026-64918?: CVE-2026-64918 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-64918 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-64918?: CVE-2026-64918 primarily affects Microsoft 365 Apps. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-64918?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-64918 published?: CVE-2026-64918 was published on 2026-09-08 and last updated on 2026-09-09.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64918

Affected products (10)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
cpe:2.3:a:microsoft:office_2016:-:*:*:*:-:*:x64:*
cpe:2.3:a:microsoft:office_2016:-:*:*:*:-:*:x86:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x86:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*

More vulnerabilities in Microsoft 365 Apps

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