CVE-2020-0903Network attack vector

Authenticated script execution via unsanitized web requests

Published Mar 12, 2020 · Updated Feb 28, 2025

Cross-site scripting in Microsoft Exchange Server 2016 and 2019 allows remote authenticated users to execute script via a crafted web request. Microsoft has disclosed only that Exchange fails to sanitize the specially crafted request and has not identified the affected handler or field. Exploitation requires low-privileged authentication and user interaction, and the resulting script can read or alter data in the victim's browser context.

CVSS severity5.4
Medium
EPSS probability1.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Microsoft Exchange Server 2016 and 2019 allows remote authenticated users to execute script via a crafted web request. Microsoft has disclosed only that Exchange fails to sanitize the specially crafted request and has not identified the affected handler or field. Exploitation requires low-privileged authentication and user interaction, and the resulting script can read or alter data in the victim's browser context.

The record

CVE
CVE-2020-0903
Published
Mar 12, 2020
Updated
Feb 28, 2025
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 4
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 12, 2020CVE publishedPublication date reported by the CVE source.
  2. Feb 28, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 4version=unspecified
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 3version=unspecified
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 14version=unspecified
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 15version=unspecified

Published CVSS scores

5.4CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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