How severe is CVE-2018-8558?

CVE-2018-8558 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2018-8558 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-8558?

CVE-2018-8558 primarily affects Microsoft Office. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-8558?

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

When was CVE-2018-8558 published?

CVE-2018-8558 was published on 2018-11-14 and last updated on 2026-06-17.

CVE-2018-8558

CVE-2018-8558 is a medium-severity vulnerability in Microsoft Office 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-200.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Microsoft Office
Published: 2018-11-14
Last modified: 2026-06-17

Description

An information disclosure vulnerability exists when Microsoft Outlook fails to respect "Default link type" settings configured via the SharePoint Online Admin Center, aka "Microsoft Outlook Information Disclosure Vulnerability." This affects Office 365 ProPlus, Microsoft Office. This CVE ID is unique from CVE-2018-8579.

Frequently asked questions

What is CVE-2018-8558?: An information disclosure vulnerability exists when Microsoft Outlook fails to respect "Default link type" settings configured via the SharePoint Online Admin Center, aka "Microsoft Outlook Information Disclosure Vulnerability." This affects Office 365 ProPlus, Microsoft Office. This CVE ID is unique from CVE-2018-8579.
How severe is CVE-2018-8558?: CVE-2018-8558 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2018-8558 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-8558?: CVE-2018-8558 primarily affects Microsoft Office. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-8558?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2018-8558 published?: CVE-2018-8558 was published on 2018-11-14 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_365_proplus:-:*:*:*:*:*:*:*

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