CVE-2021-39393Public exploitNetwork attack vector

Browser script execution via unfiltered Markdown payload

Published Aug 26, 2022 · Updated Aug 4, 2024

Cross-site scripting in the mm-wiki 0.2.1 markdown editor allows remote attackers to execute script in a user's browser. The editor accepts an inserted XSS payload and renders it as active content without filtering the user-controlled input. A user must view the affected output; public sources do not establish whether the payload persists or what session data or actions become accessible.

CVSS severity6.1
Medium
EPSS probability0.58%
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 the mm-wiki 0.2.1 markdown editor allows remote attackers to execute script in a user's browser. The editor accepts an inserted XSS payload and renders it as active content without filtering the user-controlled input. A user must view the affected output; public sources do not establish whether the payload persists or what session data or actions become accessible.

The record

CVE
CVE-2021-39393
Published
Aug 26, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 26, 2022CVE 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1NIST NVDCVSS: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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
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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