CVE-2020-19947Public exploitNetwork attack vector

Browser script execution via unsafe EMBED rendering

Published Mar 16, 2023 · Updated Feb 26, 2025

DOM-based cross-site scripting in Markdown Edit allows remote attackers to run script in a user's browser through crafted edit input. The preview path converts untrusted Markdown to HTML and renders an EMBED element whose data-URI SVG contains executable script without neutralizing it. Execution requires a user to render the crafted content, after which the script runs in the Markdown Edit page's browser context with that page's privileges.

CVSS severity9.6
Critical
EPSS probability0.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM-based cross-site scripting in Markdown Edit allows remote attackers to run script in a user's browser through crafted edit input. The preview path converts untrusted Markdown to HTML and renders an EMBED element whose data-URI SVG contains executable script without neutralizing it. Execution requires a user to render the crafted content, after which the script runs in the Markdown Edit page's browser context with that page's privileges.

The record

CVE
CVE-2020-19947
Published
Mar 16, 2023
Updated
Feb 26, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 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

9.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
9.6CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/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
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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