CVE-2021-42041Public exploitNetwork attack vector

Stored XSS via unescaped setchange log message

Published Oct 6, 2021 · Updated Aug 4, 2024

Stored cross-site scripting in CentralAuth for MediaWiki 1.36.2 and earlier allows remote authenticated users to execute JavaScript in browsers. The setchange log substitutes rightsnone message text for empty parameters and passes that text into log output without HTML escaping. Planting the payload requires editinterface permission, and execution requires another user to view the affected Special:Log or Special:WikiSets page.

CVSS severity6.1
Medium
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in CentralAuth for MediaWiki 1.36.2 and earlier allows remote authenticated users to execute JavaScript in browsers. The setchange log substitutes rightsnone message text for empty parameters and passes that text into log output without HTML escaping. Planting the payload requires editinterface permission, and execution requires another user to view the affected Special:Log or Special:WikiSets page.

The record

CVE
CVE-2021-42041
Published
Oct 6, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Oct 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.0Rapid7AV:N/AC:M/Au:N/C:N/I:P/A:N
6.1OSVCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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.

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1203Exploitation for Client Execution

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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