CVE-2026-66843
html_sanitize_ex HTML5 scrubber keeps attacker-supplied `<object>` elements, allowing untrusted content embedding
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 1.5.3.
INFO
Published Date :
Aug. 6, 2026, 4:16 p.m.
Last Modified :
Aug. 6, 2026, 4:16 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Affected Products
The following products are affected by CVE-2026-66843
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | LOW | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | LOW | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update html_sanitize_ex to version 1.5.3 or later.
- Validate object element data attribute handling.
- Restrict URIs within data attributes.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-66843.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-66843 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-66843
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-66843 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-66843 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Aug. 06, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '0.3.1', 'lessThan': '1.5.3', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/html_sanitize_ex', 'packageName': 'html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}, {'cpes': ['cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/rrrene/html_sanitize_ex', 'vendor': 'rrrene', 'modules': ['Elixir.HtmlSanitizeEx.Scrubber.HTML5', 'Elixir.HtmlSanitizeEx'], 'product': 'html_sanitize_ex', 'versions': [{'status': 'affected', 'version': '8976d64ea0b77d26093a94a43ec48a3978e8d028', 'lessThan': 'bec27fec4de99e40c68c4285a610e09e791a3eaf', 'versionType': 'git'}], 'packageURL': 'pkg:github/rrrene/html_sanitize_ex', 'packageName': 'rrrene/html_sanitize_ex', 'programFiles': ['lib/html_sanitize_ex/scrubber/html5.ex', 'lib/html_sanitize_ex.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"}, {'name': "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"}, {'name': "'Elixir.HtmlSanitizeEx':html5/1"}]}] Added 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 1.5.3. Added CVSS V4.0 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 Added CWE CWE-829 Added Reference https://cna.erlef.org/cves/CVE-2026-66843.html Added Reference https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf Added Reference https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-66843