Executive brief
Astro is a web framework used for building content-driven websites. A vulnerability in its RSS feed generation package allows attackers to inject malicious content into a site's RSS feed. This could be used to redirect users to malicious websites or display fake information to subscribers, potentially damaging a site's reputation or leading to phishing attacks.
Technical details
An XML injection vulnerability exists in the @astrojs/rss package due to improper neutralization of XML special characters. The 'source.title' and 'enclosure.type' fields are interpolated directly into XML template strings without escaping before being processed by fast-xml-parser. An attacker who can control these values (e.g., via a CMS or user-submitted content) can break out of XML attributes or elements to inject arbitrary nodes, such as malicious <link> tags. This is particularly impactful in Server-Side Rendering (SSR) mode, where the poisoned feed is served to all subscribers. The issue is fixed in version 4.0.19 by switching to structured XML object serialization.
Affected products
- Astro @astrojs/rss >= 1.0.0, < 4.0.19
Timeline
- 2026-06-26: patched: Fix merged into main branch
- 2026-06-30: patched: Version 4.0.19 released
- 2026-07-15: advisory: GitHub Security Advisory published
- 2026-07-27: disclosed: CVE published to NVD