CVE-2025-51691Public exploitNetwork attack vector

Browser code execution via unsanitized Markdown rendering

Published Aug 13, 2025 · Updated Aug 13, 2025

Cross-site scripting in MarkTwo commit e3a1d3f90cce4ea9c26efcbbf3a1cbfb9dcdb298 allows remote attackers to run browser code via editor input. The editor renders user-supplied Markdown without sanitizing embedded script content, allowing the browser to interpret the resulting markup. A victim must render the crafted document; execution occurs in that victim's browser context and can expose session or credential data.

CVSS severity6.1
Medium
EPSS probability0.40%
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 MarkTwo commit e3a1d3f90cce4ea9c26efcbbf3a1cbfb9dcdb298 allows remote attackers to run browser code via editor input. The editor renders user-supplied Markdown without sanitizing embedded script content, allowing the browser to interpret the resulting markup. A victim must render the crafted document; execution occurs in that victim's browser context and can expose session or credential data.

The record

CVE
CVE-2025-51691
Published
Aug 13, 2025
Updated
Aug 13, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 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

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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