CVE-2026-66843

Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase "javascript:", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive. This is not unconditional cross-site scripting. A javascript: URL does not execute through <object data> in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path. This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://cna.erlef.org/cves/CVE-2026-66843.html	Patch Third Party Advisory
https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf	Patch
https://github.com/rrrene/html_sanitize_ex/commit/ce038aa1af5a960d50f8eb5d368cc57bb2b9a9f0
https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj	Broken Link
https://osv.dev/vulnerability/EEF-CVE-2026-66843	Patch Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:rrrene:htmlsanitizeex:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-08-06 16:16

Updated : 2026-08-19 12:18

NVD link : CVE-2026-66843

Mitre link : CVE-2026-66843

CVE.ORG link : CVE-2026-66843

JSON object : View

Products Affected

rrrene

htmlsanitizeex

CWE

CWE-829

Inclusion of Functionality from Untrusted Control Sphere

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