{"id":"GHSA-8j5q-mfj2-5q9q","revision":"fdcc2dcd418b4668833fc2302f4621cd","records":[{"revision":"fdcc2dcd418b4668833fc2302f4621cd","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-8j5q-mfj2-5q9q","aliases":["CVE-2026-59728"],"title":"@astrojs/rss: XML Injection via Unescaped RSS Feed Fields","description":"## Summary\n\nIn `@astrojs/rss`, the `source.title` and `enclosure.type` item fields are interpolated directly into XML template strings without XML-character escaping before being parsed by `fast-xml-parser`. An attacker who controls these field values can inject arbitrary XML elements into the generated RSS feed.\n\n## Details\n\nTwo fields in `packages/astro-rss/src/index.ts` are affected:\n\n### `source.title`\n\n```typescript\nitem.source = parser.parse(\n  `<source url=\"${result.source.url}\">${result.source.title}</source>`,\n).source;\n```\n\n`source.title` is validated only as `z.string()`, with no restriction on XML special characters. A value containing `</source>` followed by arbitrary XML is parsed as real XML elements, merging injected nodes into the RSS item.\n\n### `enclosure.type`\n\n```typescript\nitem.enclosure = parser.parse(\n  `<enclosure url=\"${enclosureURL}\" length=\"${result.enclosure.length}\" type=\"${result.enclosure.type}\"/>`,\n).enclosure;\n```\n\n`enclosure.type` is also `z.string()` and is interpolated into an XML attribute without escaping. A value containing `\"` followed by additional XML can break out of the attribute and inject extra elements.\n\n## Proof of Concept\n\n`source.title` injection:\n\n```javascript\nsource: {\n  url: 'https://legit.example.com',\n  title: '</source><item><title>INJECTED</title><link>https://evil.com</link></item><source>',\n}\n// Result: RSS feed contains an injected <item> element with an evil.com link\n```\n\n`enclosure.type` injection:\n\n```javascript\nenclosure: {\n  url: 'https://example.com/a.mp3',\n  length: 0,\n  type: 'audio/mpeg\" /><link>https://evil.example.com</link><enclosure fake=\"',\n}\n// Result: RSS feed contains an injected <link> element\n```\n\nBoth injections were confirmed with `fast-xml-parser`: the injected `\"link\": \"https://evil.com\"` appears in the parsed output.\n\n## Impact\n\nAn attacker who can control `source.title` or `enclosure.type` values (e.g., via a CMS, database, or user-submitted content that populates `RSSFeedItem`) can inject arbitrary XML into the generated RSS feed. This corrupts feed structure, injects false metadata (e.g., a fake `<link>` pointing to a malicious URL), and can cause feed readers to misparse or display attacker-controlled content. In SSR mode (`output: 'server'`), the poisoned feed is served on every request to all subscribers.\n\n## Patches\n\nFixed in `@astrojs/rss@4.0.19`.","state":0,"publishedAt":"2026-07-20T23:21:47+00:00","modifiedAt":"2026-08-12T20:45:07.7382331+00:00","affected":[{"ecosystem":"npm","name":"@astrojs/rss","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"1.0.0"},{"kind":"fixed","version":"4.0.19"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/withastro/astro/security/advisories/GHSA-8j5q-mfj2-5q9q","https://nvd.nist.gov/vuln/detail/CVE-2026-59728","https://github.com/withastro/astro/pull/17209","https://github.com/withastro/astro/commit/fbcfa039dfe3d700b239f595a6c55ee35e45bd06","https://github.com/withastro/astro","https://github.com/withastro/astro/releases/tag/@astrojs/rss@4.0.19"],"sourceUrl":"https://github.com/advisories/GHSA-8j5q-mfj2-5q9q","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-8j5q-mfj2-5q9q","identifiers":["GHSA-8j5q-mfj2-5q9q","CVE-2026-59728"]},"retained":false,"historicalAffected":[]}],"coverage":[]}