CVE-2024-21535Public exploitNetwork attack vector

Cross-site scripting via unsanitized iframe src

Published Oct 15, 2024 · Updated Oct 15, 2024

Cross-site scripting in markdown-to-jsx before 7.4.0 allows remote attackers to execute JavaScript through a malicious iframe src. The attributeValueToJSXPropValue function sanitized href values but passed src values to JSX unchanged, allowing a JavaScript URL to reach an iframe. A host application must render attacker-controlled Markdown and a user must view the result; the script then runs in that page context and can read or modify data available there.

CVSS severity6.1
Medium
EPSS probability0.49%
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 markdown-to-jsx before 7.4.0 allows remote attackers to execute JavaScript through a malicious iframe src. The attributeValueToJSXPropValue function sanitized href values but passed src values to JSX unchanged, allowing a JavaScript URL to reach an iframe. A host application must render attacker-controlled Markdown and a user must view the result; the script then runs in that page context and can read or modify data available there.

The record

CVE
CVE-2024-21535
Published
Oct 15, 2024
Updated
Oct 15, 2024
Vendor
Quantizor
Product
markdown-to-jsx
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 15, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 15, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <7.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Quantizor · markdown-to-jsxversion=0 <7.4.0

Published CVSS scores

5.3GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
6.1SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1NVDCVSS: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')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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