How severe is CVE-2018-8378?

CVE-2018-8378 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2018-8378 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-8378?

CVE-2018-8378 primarily affects Microsoft Excel Viewer. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-8378?

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

When was CVE-2018-8378 published?

CVE-2018-8378 was published on 2018-08-15 and last updated on 2026-06-17.

CVE-2018-8378

CVE-2018-8378 is a medium-severity vulnerability in Microsoft Excel Viewer with a CVSS 3.x base score of 5.5. 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-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.3
EPSS exploit prediction: 7% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Microsoft Excel Viewer
Published: 2018-08-15
Last modified: 2026-06-17

Description

An information disclosure vulnerability exists when Microsoft Office software reads out of bound memory due to an uninitialized variable, which could disclose the contents of memory, aka "Microsoft Office Information Disclosure Vulnerability." This affects Word, Microsoft SharePoint Server, Microsoft Office Word Viewer, Microsoft Excel Viewer, Microsoft SharePoint, Microsoft Office.

Frequently asked questions

What is CVE-2018-8378?: An information disclosure vulnerability exists when Microsoft Office software reads out of bound memory due to an uninitialized variable, which could disclose the contents of memory, aka "Microsoft Office Information Disclosure Vulnerability." This affects Word, Microsoft SharePoint Server, Microsoft Office Word Viewer, Microsoft Excel Viewer, Microsoft SharePoint, Microsoft Office.
How severe is CVE-2018-8378?: CVE-2018-8378 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2018-8378 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 7% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-8378?: CVE-2018-8378 primarily affects Microsoft Excel Viewer. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-8378?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-8378 published?: CVE-2018-8378 was published on 2018-08-15 and last updated on 2026-06-17.

References

Affected products (14)

cpe:2.3:a:microsoft:excel_viewer:2007:sp3:*:*:*:*:*:*
cpe:2.3:a:microsoft:office:2010:sp2:*:*:*:*:*:*
cpe:2.3:a:microsoft:office:2013:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:office:2013:sp1:*:*:rt:*:*:*
cpe:2.3:a:microsoft:office:2016:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:office:2016:*:*:*:click-to-run:*:*:*
cpe:2.3:a:microsoft:office_compatibility_pack:-:sp3:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_web_apps:2010:sp2:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_web_apps:2013:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_word_viewer:-:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:sharepoint_enterprise_server_2013:-:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:sharepoint_enterprise_server_2016:-:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:sharepoint_server:2013:sp1:*:*:*:*:*:*
cpe:2.3:a:microsoft:word_automation_services:-:*:*:*:*:*:*:*

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