How severe is CVE-2018-16793?

CVE-2018-16793 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2018-16793 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-16793?

CVE-2018-16793 primarily affects Microsoft Exchange Server. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-16793?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-16793 published?

CVE-2018-16793 was published on 2018-09-21 and last updated on 2026-06-17.

CVE-2018-16793

CVE-2018-16793 is a high-severity vulnerability in Microsoft Exchange Server with a CVSS 3.x base score of 8.6. Its EPSS exploit-prediction score of 11% places it in the 95th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-918.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 5.0
EPSS exploit prediction: 11% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-918
Affected product: Microsoft Exchange Server
Published: 2018-09-21
Last modified: 2026-06-17

Description

Rollup 18 for Microsoft Exchange Server 2010 SP3 and previous versions has an SSRF vulnerability via the username parameter in /owa/auth/logon.aspx in the OWA (Outlook Web Access) login page.

Frequently asked questions

What is CVE-2018-16793?: Rollup 18 for Microsoft Exchange Server 2010 SP3 and previous versions has an SSRF vulnerability via the username parameter in /owa/auth/logon.aspx in the OWA (Outlook Web Access) login page.
How severe is CVE-2018-16793?: CVE-2018-16793 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2018-16793 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-16793?: CVE-2018-16793 primarily affects Microsoft Exchange Server. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-16793?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-16793 published?: CVE-2018-16793 was published on 2018-09-21 and last updated on 2026-06-17.

References

Affected products (18)

cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup1:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup10:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup11:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup12:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup13:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup14:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup15:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup16:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup17:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup18:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup2:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup3:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup4:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup5:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup6:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup7:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup8:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2010:sp3_rollup9:*:*:*:*:*:*

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