CVE-2020-21058Public exploitNetwork attack vector

Code execution via unsandboxed Mermaid iframe

Published Jun 20, 2023 · Updated Dec 10, 2024

Cross-site scripting in Typora 0.9.79 allows remote attackers to execute arbitrary code when a crafted Mermaid diagram is opened. Mermaid rendering accepts an iframe with attacker-controlled srcdoc without sandboxing, allowing embedded script to access Electron's process binding and spawn a program. A victim must open the crafted document; the demonstrated command-execution payload targets Windows, while script execution was also tested on macOS.

CVSS severity6.1
Medium
EPSS probability0.57%
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 Typora 0.9.79 allows remote attackers to execute arbitrary code when a crafted Mermaid diagram is opened. Mermaid rendering accepts an iframe with attacker-controlled srcdoc without sandboxing, allowing embedded script to access Electron's process binding and spawn a program. A victim must open the crafted document; the demonstrated command-execution payload targets Windows, while script execution was also tested on macOS.

The record

CVE
CVE-2020-21058
Published
Jun 20, 2023
Updated
Dec 10, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, CAPEC-63, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 20, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 10, 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

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

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')
CAPEC-63Cross-Site Scripting (XSS)
T1204.002User Execution: Malicious 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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