Vulnerability Database

362,557

Total vulnerabilities in the database

CVE-2026-59728 — @astrojs / rss

XML Injection (aka Blind XPath Injection)

Summary

In @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.

Details

Two fields in packages/astro-rss/src/index.ts are affected:

source.title

item.source = parser.parse( `<source url="${result.source.url}">${result.source.title}</source>`, ).source;

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.

enclosure.type

item.enclosure = parser.parse( `<enclosure url="${enclosureURL}" length="${result.enclosure.length}" type="${result.enclosure.type}"/>`, ).enclosure;

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.

Proof of Concept

source.title injection:

source: { url: 'https://legit.example.com', title: '</source><item><title>INJECTED</title><link>https://evil.com</link></item><source>', } // Result: RSS feed contains an injected <item> element with an evil.com link

enclosure.type injection:

enclosure: { url: 'https://example.com/a.mp3', length: 0, type: 'audio/mpeg" /><link>https://evil.example.com</link><enclosure fake="', } // Result: RSS feed contains an injected <link> element

Both injections were confirmed with fast-xml-parser: the injected "link": "https://evil.com" appears in the parsed output.

Impact

An 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.

Patches

Fixed in @astrojs/[email protected].

CVSS v3:

  • Severity: Low
  • Score: 4.3
  • AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CWEs:

OWASP TOP 10:

Frequently Asked Questions

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CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

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