CVE-2019-20374Public exploitNetwork attack vector

Code execution via Mermaid mutation XSS

Published Jan 9, 2020 · Updated Aug 5, 2024

Mutation XSS in Typora through 0.9.9.31.2 on macOS and 0.9.81 on Linux allows attackers to execute code via Mermaid blocks. Typora passes Mermaid HTML labels through bundled DOMPurify 1.0.4, whose attribute filter fails to remove namespace-switching end-tag patterns, allowing an error handler to execute. Opening a crafted Markdown file is required, after which code runs unsandboxed with the desktop user's privileges.

CVSS severity9.6
Critical
EPSS probability2.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Mutation XSS in Typora through 0.9.9.31.2 on macOS and 0.9.81 on Linux allows attackers to execute code via Mermaid blocks. Typora passes Mermaid HTML labels through bundled DOMPurify 1.0.4, whose attribute filter fails to remove namespace-switching end-tag patterns, allowing an error handler to execute. Opening a crafted Markdown file is required, after which code runs unsandboxed with the desktop user's privileges.

The record

CVE
CVE-2019-20374
Published
Jan 9, 2020
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 9, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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

6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.3MITRECVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
9.6NVDCVSS: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
T1204.002Malicious File

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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