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 inter

mediumCVSS 4.3CVE-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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 4.3
Published: 2026-07-27
Last updated: 2026-07-28
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-59728

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-597280.27% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 19% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-59728	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

mediumGHSA-8j5q-mfj2-5q9q: @astrojs/rss: XML Injection via Unescaped RSS Feed Fieldsghsa

Recent advisories for Astro is a

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

unknownCVE-2026-59730: Astro is a web framework for content-driven websites. In versions 8.1.0 through 11.0.1, when t…nvd · 2026-07-27
unknownCVE-2026-59729: Astro is a web framework for content-driven websites. Versions prior to 7.0.6 are vulnerable t…nvd · 2026-07-27
unknownCVE-2026-59727: Astro is a web framework for content-driven websites. In versions 3.10.0 through 7.0.3, when a…nvd · 2026-07-27
mediumGHSA-8mv7-9c27-98vc: Astro: composable `astro/hono` pipeline bypasses `security.checkOrigin` when `middleware(…ghsa · 2026-07-20
mediumGHSA-f48w-9m4c-m7f5: Astro: XSS via unescaped spread attribute names in renderHTMLElement (incomplete fix for …ghsa · 2026-07-20
lowGHSA-7pw4-f3q4-r2p2: Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islan…ghsa · 2026-07-20