Dashboard / CVE-2026-66843

CVE-2026-66843

LOW
INFO Priority: 0.01 BB Relevance: 55/100
Published: 2026-08-06 Modified: 2026-10-24 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: Passive
S: X
AT: Present
VC: None
VI: None
VA: None

Description

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
rrrene htmlsanitizeex 0.3.1 – 1.5.3

References & Advisories (5)

Bug Bounty Relevance

55 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity

CVSS Score

2.3 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.51%
Raw Score 0.005120
Percentile 43.6%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00512
2026-10-28
0.00512

Intelligence Sources

nvd ref →

External Links