CVE-2026-59728
Astro is a web framework for content-driven websites. In versions 1.0.0 through 4.0.18, the source.title and enclosure.type item fields in packages/astro-rss/src/index.ts are interpolated directly into XML template strings without XML-character escaping before being parsed by fast-xml-parser. Both fields are validated only as z.string(), placing no restriction on XML special characters. An attacker who controls these values can inject arbitrary XML into the generated RSS feed: a value containing " can break out of an attribute (as with enclosure.type), and a value containing </source> can close an element early and inject additional nodes (as with source.title). This corrupts feed structure, injects false metadata (for example, 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. This issue has been fixed in version 4.0.19.
Scoring
- Severity
- MEDIUM
- CVSS base score
- 4.3
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- EPSS probability
- 0.27%
- CWE
- CWE-91
- Published
- 2026-07-27
- Last modified
- 2026-07-28
Affected products
- withastro astro
Weakness type
Related vulnerabilities
- CVE-2026-2310 — IBM webMethods Integration Server is vulnerable to an XML external entity injection (XXE) attack when processing XML data
- CVE-2026-83618 — xmldom: requireWellFormed DocType publicId/systemId validation is bypassable via an embedded line terminator
- CVE-2026-83617 — xmldom: requireWellFormed element/attribute name validation is bypassable via an embedded line terminator
- CVE-2026-83616 — xmldom: Processing Instruction Target Injection Bypasses requireWellFormed
- CVE-2026-83609 — xmldom: Creation-time XML Name/QName validation is bypassable via an embedded line terminator, allowing injection on the default serialization path
- CVE-2026-83608 — xmldom: DocType `name` Injection Bypasses requireWellFormed
- CVE-2026-83607 — xmldom: Element name injection via createElement() bypasses requireWellFormed
- CVE-2026-83605 — xmldom: Attribute name injection via setAttribute() bypasses requireWellFormed