CVE-2021-40289Public exploitNetwork attack vector

Stored script execution via unfiltered space tags

Published Nov 10, 2022 · Updated May 1, 2025

Stored cross-site scripting in mm-wiki 0.2.1 allows remote attackers to execute script in another user's browser via crafted space tags. The new-space POST handler accepts the tags field at /system/space/save and stores it without filtering HTML event-handler markup. Execution requires another user to view the saved space content, exposing or altering only data available to that user's browser session.

CVSS severity6.1
Medium
EPSS probability0.50%
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 mm-wiki 0.2.1 allows remote attackers to execute script in another user's browser via crafted space tags. The new-space POST handler accepts the tags field at /system/space/save and stores it without filtering HTML event-handler markup. Execution requires another user to view the saved space content, exposing or altering only data available to that user's browser session.

The record

CVE
CVE-2021-40289
Published
Nov 10, 2022
Updated
May 1, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 10, 2022CVE publishedPublication date reported by the CVE source.
  2. May 1, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1NVDCVSS: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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

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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