Script execution via trusted highlighter output
Published Aug 21, 2025 · Updated Dec 3, 2025
Cross-site scripting in markdown-it 14.1.0 allows attackers to execute JavaScript when an application uses an unsafe custom highlighter. The fenced-code renderer returns highlighter output beginning with a pre tag directly because the API requires that callback to return escaped HTML. Reachability requires an application-defined callback that passes attacker-controlled content through unescaped; the maintainer labels the report invalid and disputes that this is a library flaw.
Summary
What happened
Cross-site scripting in markdown-it 14.1.0 allows attackers to execute JavaScript when an application uses an unsafe custom highlighter. The fenced-code renderer returns highlighter output beginning with a pre tag directly because the API requires that callback to return escaped HTML. Reachability requires an application-defined callback that passes attacker-controlled content through unescaped; the maintainer labels the report invalid and disputes that this is a library flaw.
The record
- CVE
- CVE-2025-7969
- Published
- Aug 21, 2025
- Updated
- Dec 3, 2025
- Vendor
- markdown-it
- Product
- markdown-it
- Classifications
- CWE-79, T1059.007
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 21, 2025CVE publishedPublication date reported by the CVE source.
- Dec 3, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=14.1.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Fluid Attacks fenced-code highlighter PoCproof of concept · unverified
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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