CVE-2023-3550Public exploitNetwork attack vector

Administrator escalation via crafted XML stored XSS

Published Sep 25, 2023 · Updated Feb 13, 2025

Stored XSS in MediaWiki 1.40.0 allows remote authenticated users to gain administrator privileges through a crafted XML upload. Special:Upload accepts an XML file whose namespace maps a script element into XHTML, bypassing script-detection controls and storing executable JavaScript. The default configuration is unaffected; exploitation requires XML in $wgFileExtensions and an administrator to open the attacker's link.

CVSS severity9.0
Critical
EPSS probability1.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in MediaWiki 1.40.0 allows remote authenticated users to gain administrator privileges through a crafted XML upload. Special:Upload accepts an XML file whose namespace maps a script element into XHTML, bypassing script-detection controls and storing executable JavaScript. The default configuration is unaffected; exploitation requires XML in $wgFileExtensions and an administrator to open the attacker's link.

The record

CVE
CVE-2023-3550
Published
Sep 25, 2023
Updated
Feb 13, 2025
Vendor
Wikimedia Foundation
Product
MediaWiki
Classifications
CWE-79, T1098, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 25, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1.40.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Wikimedia Foundation · MediaWikiversion=1.40.0

Published CVSS scores

7.3Fluid Attacks CNACVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
9.0NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1098Account Manipulation
T1204.001Malicious Link

Public exploit references

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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