{"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":{"dateUpdated":"2026-08-03T19:04:30.556Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"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."}]}},"cveMetadata":{"assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","assignerShortName":"EEF","cveId":"CVE-2026-66296","datePublished":"2026-08-03T19:04:30.556Z","dateReserved":"2026-07-24T14:10:01.114Z","dateUpdated":"2026-08-03T19:04:30.556Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"}