{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-66370",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-08-06T10:15:01.808Z",
        "datePublished": "2026-08-06T14:49:15.841Z",
        "dateUpdated": "2026-08-19T11:51:08.771Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
                        "Elixir.HtmlSanitizeEx"
                    ],
                    "packageName": "html_sanitize_ex",
                    "packageURL": "pkg:hex/html_sanitize_ex",
                    "product": "html_sanitize_ex",
                    "programFiles": [
                        "lib/html_sanitize_ex/scrubber/html5.ex",
                        "lib/html_sanitize_ex.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"
                        },
                        {
                            "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"
                        },
                        {
                            "name": "'Elixir.HtmlSanitizeEx':html5/1"
                        }
                    ],
                    "repo": "https://github.com/rrrene/html_sanitize_ex",
                    "vendor": "rrrene",
                    "versions": [
                        {
                            "lessThan": "1.4.5",
                            "status": "affected",
                            "version": "0.3.1",
                            "versionType": "semver"
                        },
                        {
                            "lessThan": "1.5.3",
                            "status": "affected",
                            "version": "1.5.0-rc.0",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "Elixir.HtmlSanitizeEx.Scrubber.HTML5",
                        "Elixir.HtmlSanitizeEx"
                    ],
                    "packageName": "rrrene/html_sanitize_ex",
                    "packageURL": "pkg:github/rrrene/html_sanitize_ex",
                    "product": "html_sanitize_ex",
                    "programFiles": [
                        "lib/html_sanitize_ex/scrubber/html5.ex",
                        "lib/html_sanitize_ex.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':scrub_attribute/2"
                        },
                        {
                            "name": "'Elixir.HtmlSanitizeEx.Scrubber.HTML5':sanitize/1"
                        },
                        {
                            "name": "'Elixir.HtmlSanitizeEx':html5/1"
                        }
                    ],
                    "repo": "https://github.com/rrrene/html_sanitize_ex",
                    "vendor": "rrrene",
                    "versions": [
                        {
                            "changes": [
                                {
                                    "at": "a1e804ed997e780ea71d14393cf2f701330553a6",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "21394e758cb0ffe12fb9953c30fdedc6016c8f9e",
                                    "status": "unaffected"
                                }
                            ],
                            "lessThan": "*",
                            "status": "affected",
                            "version": "8976d64ea0b77d26093a94a43ec48a3978e8d028",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "configurations": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>Only <code>HtmlSanitizeEx.html5/1</code>, and custom scrubbers declared with <code>use HtmlSanitizeEx, extend: :html5</code>, allow the <code>input</code> element, and the sanitized output must be rendered to other users.</p>\n<p>The rendering page must also contain a form with an <code>id</code>, since that <code>id</code> is what the injected <code>form</code> attribute binds to.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Only `HtmlSanitizeEx.html5/1`, and custom scrubbers declared with `use HtmlSanitizeEx, extend: :html5`, allow the `input` element, and the sanitized output must be rendered to other users.\n\nThe rendering page must also contain a form with an `id`, since that `id` is what the injected `form` attribute binds to."
                        }
                    ],
                    "value": "Only HtmlSanitizeEx.html5/1, and custom scrubbers declared with use HtmlSanitizeEx, extend: :html5, allow the input element, and the sanitized output must be rendered to other users.\n\nThe rendering page must also contain a form with an id, since that id is what the injected form attribute binds to."
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "1.4.5",
                                    "versionStartIncluding": "0.3.1",
                                    "vulnerable": true
                                },
                                {
                                    "criteria": "cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "1.5.3",
                                    "versionStartIncluding": "1.5.0-rc.0",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Peter Ullrich"
                },
                {
                    "lang": "en",
                    "type": "analyst",
                    "value": "Jonatan Männchen / EEF"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "René Föhring"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the <code>form</code> and <code>formaction</code> attributes on an <code>&lt;input&gt;</code> element in sanitized HTML. HTML's <code>form</code> attribute associates an input with any form on the page by its <code>id</code> even when the input sits outside that form, and <code>formaction</code> on a submit control overrides the owning form's <code>action</code>. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.</p>\n<p>No script executes. The scrubber allows neither <code>form</code> nor <code>button</code>, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an <code>id</code>.</p>\n<p>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.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the `form` and `formaction` attributes on an `<input>` element in sanitized HTML. HTML's `form` attribute associates an input with any form on the page by its `id` even when the input sits outside that form, and `formaction` on a submit control overrides the owning form's `action`. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.\n\nNo script executes. The scrubber allows neither `form` nor `button`, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an `id`.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3."
                        }
                    ],
                    "value": "URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing.\n\nNo script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id.\n\nThis issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-154",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-154 Resource Location Spoofing"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "attackVector": "NETWORK",
                        "baseScore": 4.8,
                        "baseSeverity": "MEDIUM",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "HIGH",
                        "subIntegrityImpact": "LOW",
                        "userInteraction": "ACTIVE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "NONE",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-601",
                            "description": "CWE-601 URL Redirection to Untrusted Site ('Open Redirect')",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-08-19T11:51:08.771Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-w3f9-jjhw-wwvq"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-66370.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66370"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/rrrene/html_sanitize_ex/commit/a1e804ed997e780ea71d14393cf2f701330553a6"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/rrrene/html_sanitize_ex/commit/21394e758cb0ffe12fb9953c30fdedc6016c8f9e"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "html_sanitize_ex HTML5 scrubber keeps attacker-supplied form-association attributes, allowing form hijacking",
            "workarounds": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>Sanitize with <code>basic_html/1</code>, <code>markdown_html/1</code> or <code>strip_tags/1</code>, none of which allow <code>input</code>, or define a custom scrubber that omits it.</p>\n<p>Omitting the <code>id</code> attribute from the page's own forms, or giving them values an attacker cannot predict, removes the anchor the injected <code>form</code> attribute needs.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Sanitize with `basic_html/1`, `markdown_html/1` or `strip_tags/1`, none of which allow `input`, or define a custom scrubber that omits it.\n\nOmitting the `id` attribute from the page's own forms, or giving them values an attacker cannot predict, removes the anchor the injected `form` attribute needs."
                        }
                    ],
                    "value": "Sanitize with basic_html/1, markdown_html/1 or strip_tags/1, none of which allow input, or define a custom scrubber that omits it.\n\nOmitting the id attribute from the page's own forms, or giving them values an attacker cannot predict, removes the anchor the injected form attribute needs."
                }
            ]
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-08-06T15:42:03.803831Z",
                                "id": "CVE-2026-66370",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-08-06T15:42:09.603Z"
                }
            }
        ]
    }
}