{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-66296",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-07-24T14:10:01.114Z",
        "datePublished": "2026-08-03T19:04:30.556Z",
        "dateUpdated": "2026-08-03T19:50:27.860Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "collectionURL": "https://repo.hex.pm",
                    "cpes": [
                        "cpe:2.3:a:lud:oaskit:*:*:*:*:*:elixir:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "Elixir.Oaskit.ErrorHandler.Default"
                    ],
                    "packageName": "oaskit",
                    "packageURL": "pkg:hex/oaskit",
                    "product": "oaskit",
                    "programFiles": [
                        "lib/oaskit/error_handler/default.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.Oaskit.ErrorHandler.Default':format_reason/4"
                        },
                        {
                            "name": "'Elixir.Oaskit.ErrorHandler.Default':reason_to_html/1"
                        }
                    ],
                    "repo": "https://github.com/lud/oaskit",
                    "vendor": "lud",
                    "versions": [
                        {
                            "lessThan": "0.14.1",
                            "status": "affected",
                            "version": "0.1.0",
                            "versionType": "semver"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:lud:oaskit:*:*:*:*:*:elixir:*:*"
                    ],
                    "defaultStatus": "unaffected",
                    "modules": [
                        "Elixir.Oaskit.ErrorHandler.Default"
                    ],
                    "packageName": "lud/oaskit",
                    "packageURL": "pkg:github/lud/oaskit",
                    "product": "oaskit",
                    "programFiles": [
                        "lib/oaskit/error_handler/default.ex"
                    ],
                    "programRoutines": [
                        {
                            "name": "'Elixir.Oaskit.ErrorHandler.Default':format_reason/4"
                        },
                        {
                            "name": "'Elixir.Oaskit.ErrorHandler.Default':reason_to_html/1"
                        }
                    ],
                    "repo": "https://github.com/lud/oaskit",
                    "vendor": "lud",
                    "versions": [
                        {
                            "lessThan": "b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1",
                            "status": "affected",
                            "version": "552de8ca0ff60617bea58bcafa451892d61a161c",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:lud:oaskit:*:*:*:*:*:elixir:*:*",
                                    "versionEndExcluding": "0.14.1",
                                    "versionStartIncluding": "0.1.0",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Ludovic Dem"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Ludovic Dem"
                },
                {
                    "lang": "en",
                    "type": "analyst",
                    "value": "Jonatan Männchen / EEF"
                }
            ],
            "datePublic": "2026-07-05T00:00:00.000Z",
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler.</p>\n<p><code>Oaskit.ErrorHandler.Default.format_reason/4</code> and <code>Oaskit.ErrorHandler.Default.reason_to_html/1</code> in <code>lib/oaskit/error_handler/default.ex</code> render request-validation failures as an HTML page whenever the request's <code>Accept</code> header contains <code>html</code>, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or <code>deepObject</code> query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under <code>additionalProperties: false</code>), and the raw <code>Content-Type</code> header, reflected in unsupported-media-type errors when it fails to parse.</p>\n<p>Because browsers send <code>Accept: text/html</code> on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom <code>Content-Type</code>, or attacker-controlled script on the victim's side is required. A payload such as <code>filter[&lt;/code&gt;&lt;/h2&gt;&lt;script&gt;alert(document.domain)&lt;/script&gt;]=x</code> terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses.</p>\n<p>Both HTML error rendering and the vulnerable handler are enabled by default: <code>Oaskit.Plugs.ValidateRequest</code> defaults <code>:html_errors</code> to <code>true</code> and <code>:error_handler</code> to <code>Oaskit.ErrorHandler.Default</code>, so applications following the documented usage are affected without any opt-in.</p>\n<p>This issue affects oaskit: from 0.1.0 before 0.14.1.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler.\n\n`Oaskit.ErrorHandler.Default.format_reason/4` and `Oaskit.ErrorHandler.Default.reason_to_html/1` in `lib/oaskit/error_handler/default.ex` render request-validation failures as an HTML page whenever the request's `Accept` header contains `html`, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or `deepObject` query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under `additionalProperties: false`), and the raw `Content-Type` header, reflected in unsupported-media-type errors when it fails to parse.\n\nBecause browsers send `Accept: text/html` on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom `Content-Type`, or attacker-controlled script on the victim's side is required. A payload such as `filter[</code></h2><script>alert(document.domain)</script>]=x` terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses.\n\nBoth HTML error rendering and the vulnerable handler are enabled by default: `Oaskit.Plugs.ValidateRequest` defaults `:html_errors` to `true` and `:error_handler` to `Oaskit.ErrorHandler.Default`, so applications following the documented usage are affected without any opt-in.\n\nThis issue affects oaskit: from 0.1.0 before 0.14.1."
                        }
                    ],
                    "value": "Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler.\n\nOaskit.ErrorHandler.Default.format_reason/4 and Oaskit.ErrorHandler.Default.reason_to_html/1 in lib/oaskit/error_handler/default.ex render request-validation failures as an HTML page whenever the request's Accept header contains html, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or deepObject query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under additionalProperties: false), and the raw Content-Type header, reflected in unsupported-media-type errors when it fails to parse.\n\nBecause browsers send Accept: text/html on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom Content-Type, or attacker-controlled script on the victim's side is required. A payload such as filter[</code></h2><script>alert(document.domain)</script>]=x terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses.\n\nBoth HTML error rendering and the vulnerable handler are enabled by default: Oaskit.Plugs.ValidateRequest defaults :html_errors to true and :error_handler to Oaskit.ErrorHandler.Default, so applications following the documented usage are affected without any opt-in.\n\nThis issue affects oaskit: from 0.1.0 before 0.14.1."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-591",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-591 Reflected XSS"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 5.1,
                        "baseSeverity": "MEDIUM",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "LOW",
                        "subIntegrityImpact": "LOW",
                        "userInteraction": "ACTIVE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/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-79",
                            "description": "CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-08-03T19:04:30.556Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-66296.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66296"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/lud/oaskit/commit/b70c6b2eaf0b11bdd0bbb21b8a87dbb3d46918a1"
                }
            ],
            "source": {
                "discovery": "INTERNAL"
            },
            "title": "Reflected XSS in oaskit's default HTML error handler",
            "workarounds": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p>Disable HTML error rendering so that validation failures are returned as JSON only:</p>\n<pre><code class=\"language-elixir\">plug Oaskit.Plugs.ValidateRequest, html_errors: false\n</code></pre>\n<p>This prevents the vulnerable HTML page from being rendered at all, on any oaskit version. Alternatively, configure a custom <code>:error_handler</code> that does not emit HTML built from request-derived values.</p>"
                        },
                        {
                            "base64": false,
                            "type": "text/markdown",
                            "value": "Disable HTML error rendering so that validation failures are returned as JSON only:\n\n```elixir\nplug Oaskit.Plugs.ValidateRequest, html_errors: false\n```\n\nThis prevents the vulnerable HTML page from being rendered at all, on any oaskit version. Alternatively, configure a custom `:error_handler` that does not emit HTML built from request-derived values."
                        }
                    ],
                    "value": "Disable HTML error rendering so that validation failures are returned as JSON only:\n\nplug Oaskit.Plugs.ValidateRequest, html_errors: false\n\nThis prevents the vulnerable HTML page from being rendered at all, on any oaskit version. Alternatively, configure a custom :error_handler that does not emit HTML built from request-derived values."
                }
            ]
        },
        "adp": [
            {
                "references": [
                    {
                        "url": "https://github.com/lud/oaskit/security/advisories/GHSA-h7xw-x8wr-xpcc",
                        "tags": [
                            "exploit"
                        ]
                    }
                ],
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-08-03T19:50:03.665445Z",
                                "id": "CVE-2026-66296",
                                "options": [
                                    {
                                        "Exploitation": "poc"
                                    },
                                    {
                                        "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": "2026-08-03T19:50:27.860Z"
                }
            }
        ]
    }
}