DOMSanitizer - Incomplete data: URL Sanitization in DOMSanitizer::isDangerousUrl() Allows Base64-Encoded Payloads to Bypass href and xlink:href Validation

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-100370
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-28 21:17:10 UTC
Updated2026-09-30 19:57:08 UTC
DescriptionDOMSanitizer is a DOM/SVG/MathML Sanitizer for PHP 7.3+. Prior to version 1.0.15, the isDangerousUrl() method is responsible for rejecting dangerous URL values in the href and xlink:href attributes. The weakness is that "javascript:" is rejected as a scheme, while "data:" is rejected only when the literal substring onload appears in the URL value (/^data:.*onload/i). Because data: payloads are routinely Base64-encoded, the dangerous content (<script>, event handlers, etc.) is invisible to that substring test. A URL such as data:text/html;base64,… therefore survives in href / xlink:href, even though the decoded payload is active markup. This is an incomplete input-validation / sanitization defect in the sanitizer itself. This issue has been patched in version 1.0.15.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

EPSS: 0.002740000 probability, percentile 0.177890000 (date 2026-09-29)

Problem Types: CWE-20 | CWE-20 CWE-20: Improper Input Validation

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N
3.1CNADECLARED4.7MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Rhukster Dom-sanitizer affected < 1.0.15 Not specified

References

ReferenceSourceLinkTags
github.com/rhukster/dom-sanitizer/commit/10f97807e4501d60f63987f2e76a38c... [email protected] github.com
github.com/rhukster/dom-sanitizer/releases/tag/1.0.15 [email protected] github.com
github.com/rhukster/dom-sanitizer/commit/fb8f758b41134fc5fb2f563666f2330... [email protected] github.com
github.com/rhukster/dom-sanitizer/security/advisories/GHSA-wcj2-r6vg-rm97 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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