CVE-2026-66843: Software Security Vulnerability Vulnerability

LOW
Advisory Identifier: GHSA-6g7x-33rf-28v3
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CVSS 6.1
CWE-829
Published
Advisory Summary

CVE-2026-66843 is a LOW (CVSS 6.1) security vulnerability vulnerability (CWE-829: Inclusion of Functionality from Untrusted Control Sphere) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-66843 at a Glance

CVE Identifier CVE-2026-66843
GHSA Identifier GHSA-6g7x-33rf-28v3
Severity LOW
CVSS v3.1 Base Score 6.1
CWE Classification CWE-829: Inclusion of Functionality from Untrusted Control Sphere
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-66843

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-66843, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-829: Inclusion of Functionality from Untrusted Control Sphere, where the product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj
NVD — CVE-2026-66843 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-66843
Security Fix Commit FIX COMMIT
https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf
Security Fix Commit FIX COMMIT
https://github.com/rrrene/html_sanitize_ex/commit/ce038aa1af5a960d50f8eb5d368cc57bb2b9a9f0
cna.erlef.org/cves/cve-2026-66843... WEB
https://cna.erlef.org/cves/CVE-2026-66843.html
osv.dev/vulnerability/eef-c... WEB
https://osv.dev/vulnerability/EEF-CVE-2026-66843

Frequently Asked Questions

What is CVE-2026-66843?
CVE-2026-66843 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-829: Inclusion of Functionality from Untrusted Control Sphere.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-66843?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-66843?
CVE-2026-66843 has a CVSS v3.1 base score of 6.1 (LOW) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2026-66843?
CVE-2026-66843 is classified under CWE-829: Inclusion of Functionality from Untrusted Control Sphere (The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.).
How can I check Maven dependencies for CVE-2026-66843?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6g7x-33rf-28v3",
  "modified" : "2026-08-19T12:32:21Z",
  "published" : "2026-08-06T18:30:50Z",
  "aliases" : [ "CVE-2026-66843" ],
  "details" : "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.\n\nThis 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.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-xmm9-jc22-rcgj"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-66843"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rrrene/html_sanitize_ex/commit/bec27fec4de99e40c68c4285a610e09e791a3eaf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rrrene/html_sanitize_ex/commit/ce038aa1af5a960d50f8eb5d368cc57bb2b9a9f0"
  }, {
    "type" : "WEB",
    "url" : "https://cna.erlef.org/cves/CVE-2026-66843.html"
  }, {
    "type" : "WEB",
    "url" : "https://osv.dev/vulnerability/EEF-CVE-2026-66843"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-829" ],
    "severity" : "LOW",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-06T16:16:49Z"
  }
}