Cross-site scripting via ignored empty sanitizer options
Published Mar 27, 2026 · Updated Mar 27, 2026
Cross-site scripting in AhmedAdelFahim express-xss-sanitizer before 2.0.2 allows remote attackers to inject HTML via sanitized input. The initializeOptions logic discards explicitly empty allowedTags and allowedAttributes values, causing sanitize-html defaults to replace the restrictive policy. Exploitation requires an application to pass either empty option and render the sanitized data; the defaults permit unintended tags and links, while script execution depends on downstream usage.
Summary
What happened
Cross-site scripting in AhmedAdelFahim express-xss-sanitizer before 2.0.2 allows remote attackers to inject HTML via sanitized input. The initializeOptions logic discards explicitly empty allowedTags and allowedAttributes values, causing sanitize-html defaults to replace the restrictive policy. Exploitation requires an application to pass either empty option and render the sanitized data; the defaults permit unintended tags and links, while script execution depends on downstream usage.
The record
- CVE
- CVE-2026-33979
- Published
- Mar 27, 2026
- Updated
- Mar 27, 2026
- Vendor
- Express XSS Sanitizer project
- Product
- express-xss-sanitizer
- Classifications
- CWE-183, CWE-79, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 27, 2026CVE publishedPublication date reported by the CVE source.
- Mar 27, 2026Record 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=< 2.0.2
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
- GitHub advisory sanitizer-bypass proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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