How severe is CVE-2020-0903?

CVE-2020-0903 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2020-0903 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-0903?

CVE-2020-0903 primarily affects Microsoft Exchange Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-0903?

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

When was CVE-2020-0903 published?

CVE-2020-0903 was published on 2020-03-12 and last updated on 2026-06-17.

CVE-2020-0903

CVE-2020-0903 is a medium-severity vulnerability in Microsoft Exchange Server with a CVSS 3.x base score of 5.4. 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-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 3.5
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Microsoft Exchange Server
Published: 2020-03-12
Last modified: 2026-06-17

Description

A cross-site-scripting (XSS) vulnerability exists when Microsoft Exchange Server does not properly sanitize a specially crafted web request to an affected Exchange server, aka 'Microsoft Exchange Server Spoofing Vulnerability'.

Frequently asked questions

What is CVE-2020-0903?: A cross-site-scripting (XSS) vulnerability exists when Microsoft Exchange Server does not properly sanitize a specially crafted web request to an affected Exchange server, aka 'Microsoft Exchange Server Spoofing Vulnerability'.
How severe is CVE-2020-0903?: CVE-2020-0903 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2020-0903 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-0903?: CVE-2020-0903 primarily affects Microsoft Exchange Server. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-0903?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-0903 published?: CVE-2020-0903 was published on 2020-03-12 and last updated on 2026-06-17.

References

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0903

Affected products (4)

cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:*

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