{"id":"GHSA-f48w-9m4c-m7f5","revision":null,"records":[{"revision":"a54f5db9c94c41f2a0ea741f8d46fde6","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-59729","aliases":[],"title":"Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for CVE-2026-54298)","description":"Astro is a web framework for content-driven websites. Versions prior to 7.0.6 are vulnerable to XSS through unescaped spread attribute names in renderHTMLElement. The fix for CVE-2026-54298 (GHSA-jrpj-wcv7-9fh9) added an INVALID_ATTR_NAME_CHAR guard to addAttribute() so that spread-prop attribute names containing \"' >/= or whitespace are dropped. A second attribute-rendering path, renderHTMLElement() in packages/astro/src/runtime/server/render/dom.ts, has its own inline attribute loop that does not go through addAttribute() and was not updated. It interpolates the attribute name unescaped and only escapes the value, so untrusted prop keys spread onto a native-HTMLElement-subclass component can still break out of the attribute context. This issue has been fixed in version 7.0.6.","state":0,"publishedAt":"2026-07-27T19:38:40.372+00:00","modifiedAt":"2026-07-28T13:48:46.64+00:00","affected":[{"ecosystem":"Vendor product","name":"astro","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"withastro\",\n                    \"product\": \"astro\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 7.0.6\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":5.1,"severity":"MEDIUM"}],"references":["https://github.com/withastro/astro/security/advisories/GHSA-f48w-9m4c-m7f5","https://github.com/withastro/astro/pull/17251","https://github.com/withastro/astro/commit/5240e26c9dd91f9bc7140dcfacdb48d5a132830d","https://github.com/withastro/astro/releases/tag/astro@7.0.6"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-59729","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-59729","identifiers":["CVE-2026-59729"]},"retained":false,"historicalAffected":[]},{"revision":"070f827072da43e3a7b41ad6673e774a","observedAt":"2026-10-25T14:19:22.811+00:00","statement":{"source":"nvd","id":"CVE-2026-59729","aliases":[],"title":"Astro is a web framework for content-driven websites. Versions prior to 7.0.6 are vulnerable to XSS through unescaped spread attribute names in renderHTMLElement. The fix for CVE-2026-54298 (GHSA-jrpj-wcv7-9fh9) added an INVALID_ATTR_NAME_C…","description":"Astro is a web framework for content-driven websites. Versions prior to 7.0.6 are vulnerable to XSS through unescaped spread attribute names in renderHTMLElement. The fix for CVE-2026-54298 (GHSA-jrpj-wcv7-9fh9) added an INVALID_ATTR_NAME_CHAR guard to addAttribute() so that spread-prop attribute names containing \"' >/= or whitespace are dropped. A second attribute-rendering path, renderHTMLElement() in packages/astro/src/runtime/server/render/dom.ts, has its own inline attribute loop that does not go through addAttribute() and was not updated. It interpolates the attribute name unescaped and only escapes the value, so untrusted prop keys spread onto a native-HTMLElement-subclass component can still break out of the attribute context. This issue has been fixed in version 7.0.6.","state":0,"publishedAt":"2026-07-27T20:16:40.303+00:00","modifiedAt":"2026-10-24T13:10:00.147+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"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/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","score":5.1,"severity":"MEDIUM"}],"references":["https://github.com/withastro/astro/commit/5240e26c9dd91f9bc7140dcfacdb48d5a132830d","https://github.com/withastro/astro/pull/17251","https://github.com/withastro/astro/releases/tag/astro@7.0.6","https://github.com/withastro/astro/security/advisories/GHSA-f48w-9m4c-m7f5"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-59729","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-79"],"productCriteria":[],"sourceDates":{"published":"2026-07-27T20:16:40.303","lastModified":"2026-10-24T13:10:00.147"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-59729","identifiers":["CVE-2026-59729"]},"retained":false,"historicalAffected":[]},{"revision":"9d74e32e6fc9431fa3b41d7e1a9bef9d","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-f48w-9m4c-m7f5","aliases":["CVE-2026-59729"],"title":"Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for CVE-2026-54298)","description":"## Summary\n\nThe fix for CVE-2026-54298 (GHSA-jrpj-wcv7-9fh9) added an `INVALID_ATTR_NAME_CHAR` guard to `addAttribute()` so that spread-prop attribute names containing `\"' >/=` or whitespace are dropped. A second attribute-rendering path, `renderHTMLElement()` in `packages/astro/src/runtime/server/render/dom.ts`, has its own inline attribute loop that does not go through `addAttribute()` and was not updated. It interpolates the attribute name unescaped and only escapes the value, so untrusted prop keys spread onto a native-`HTMLElement`-subclass component can still break out of the attribute context, resulting in XSS.\n\n## Details\n\n`renderHTMLElement` builds attributes directly:\n\n```js\nfor (const attr in props) {\n  attrHTML += ` ${attr}=\"${toAttributeString(await props[attr])}\"`;\n}\n```\n\nThe attribute name (`attr`) is interpolated raw; only the value is escaped via `toAttributeString`. By contrast, the hardened `addAttribute` in `util.ts` rejects invalid names:\n\n```js\nif (INVALID_ATTR_NAME_CHAR.test(key)) { return ''; } // /[\\s\"'>/=]/\n```\n\n`renderHTMLElement` is reached from `component.ts` when the component is a native `HTMLElement` subclass:\n\n```js\nif (!renderer && typeof HTMLElement === 'function' && componentIsHTMLElement(Component)) {\n  const output = await renderHTMLElement(result, Component, _props, slots);\n}\n```\n\nwhere `_props` carries spread props verbatim.\n\n### Reachability\n\nThe branch only runs when `typeof HTMLElement === 'function'` at SSR time. In default Node SSR `HTMLElement` is `undefined`, so the branch is dead. It becomes reachable when the SSR runtime exposes a global `HTMLElement` (Deno, Bun with a DOM shim, or jsdom/happy-dom in Node) **and** a class extending `HTMLElement` is used directly as an Astro component that receives untrusted-keyed spread props.\n\n## Proof of Concept\n\nGiven malicious spread props:\n\n```js\nconst maliciousProps = {\n  'onmouseover=alert(document.domain) x': 'y',\n  'x><script>alert(1)</script>': 'z',\n};\n```\n\n- `addAttribute` (post-fix) → `<my-el></my-el>` (key stripped — safe)\n- `renderHTMLElement` → `<my-el onmouseover=alert(document.domain) x=\"y\" x><script>alert(1)</script>=\"z\"></my-el>` (handler + `<script>` injected — XSS)\n\nEquivalent Astro template, served by an SSR runtime that defines a global `HTMLElement`:\n\n```astro\n---\nimport MyElement from '../MyElement.js'; // class MyElement extends HTMLElement {}\nconst userInput = Astro.url.searchParams;  // untrusted keys\n---\n<MyElement {...Object.fromEntries(userInput)} />\n```\n\n## Impact\n\nCross-site scripting (CWE-79) via attribute-name breakout — the same vulnerability class as CVE-2026-54298, in a code path its fix did not cover. An attacker who controls the keys of an object spread onto a native-`HTMLElement`-subclass component can inject arbitrary event-handler attributes or sibling elements (including `<script>`) into the SSR output. Reachability is constrained by the runtime and component preconditions described above.","state":0,"publishedAt":"2026-07-20T23:21:58+00:00","modifiedAt":"2026-08-12T20:45:07.6868475+00:00","affected":[{"ecosystem":"npm","name":"astro","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"7.0.6"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/withastro/astro/security/advisories/GHSA-f48w-9m4c-m7f5","https://nvd.nist.gov/vuln/detail/CVE-2026-59729","https://github.com/withastro/astro/pull/17251","https://github.com/withastro/astro/commit/5240e26c9dd91f9bc7140dcfacdb48d5a132830d","https://github.com/withastro/astro","https://github.com/withastro/astro/releases/tag/astro@7.0.6"],"sourceUrl":"https://github.com/advisories/GHSA-f48w-9m4c-m7f5","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-f48w-9m4c-m7f5","identifiers":["GHSA-f48w-9m4c-m7f5","CVE-2026-59729"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-43321610382942b8ad8c85917eab1546","complete":false,"records":4735,"lastAttemptAt":"2026-10-26T05:26:59.285199+00:00","lastSuccessAt":"2026-10-24T23:18:49.862+00:00","error":"InvalidDataException","lastVerifiedAt":"2026-10-24T23:18:49.862+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":4764,"expectedIdentifiers":13474},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. 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