CVE Catalog

CVE-2026-61784

MediumCVSS 6.1
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.17%

5th percentile - higher than 5% of all known CVEs

Summary

xhtml-purifier versions prior to 0.4.3 do not HTML-entity-encode attribute values when serializing sanitized output. In attributeString() the attribute value is concatenated directly into a double-quoted attribute, so an attacker-controlled value can include a double-quote to break out and inject an additional attribute, such as a JavaScript event handler.

Risk Assessment

The injected handler survives sanitization and executes when the output is rendered, which is a sanitizer bypass leading to cross-site scripting. This may enable session theft or actions performed on behalf of the user.

Recommendation

Update xhtml-purifier to version 0.4.3 or later, which HTML-entity-encodes attribute values before serialization. Verify that your application does not render untrusted HTML through vulnerable versions.

Related vulnerabilities

Original NVD description (English source)

xhtml-purifier is a Node.js library to take in raw/unknown/untrusted HTML and output cleaned, purified, trusted HTML. Versions prior to 0.4.3 do not HTML-entity-encode attribute values when serializing its sanitized output. In attributeString() (XHTMLPurifier.js, around line 148) the attribute value is concatenated directly into a double-quoted attribute without encoding. As a result, an attacker-controlled value in any allowed attribute (class, style, title, alt, src, href) can include a double-quote character to break out of the attribute and inject an additional attribute, such as a JavaScript event handler (for example onmouseover or onerror). The injected handler survives sanitization and executes when the output is rendered, which is a sanitizer bypass leading to cross-site scripting. The fix in version 0.4.3 HTML-entity-encodes attribute values before serialization.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS