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.
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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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- Puntuación base: 4.3
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.37%
- Percentil entre todas las CVEs puntuadas: 29
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-91
Referencias
- https://github.com/withastro/astro/commit/fbcfa039dfe3d700b239f595a6c55ee35e45bd06
- https://github.com/withastro/astro/pull/17209
- https://github.com/withastro/astro/releases/tag/@astrojs/rss@4.0.19
- https://github.com/withastro/astro/security/advisories/GHSA-8j5q-mfj2-5q9q
- https://github.com/withastro/astro/security/advisories/GHSA-8j5q-mfj2-5q9q
JSON original (NVD)
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{
"id": "CVE-2026-59728",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-59728",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-07-28T14:27:36.621244Z"
}
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 4.3,
"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N",
"integrityImpact": "LOW",
"userInteraction": "REQUIRED",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "NONE",
"confidentialityImpact": "NONE"
},
"impactScore": 1.4,
"exploitabilityScore": 2.8
}
]
},
"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
{
"vendor": "withastro",
"product": "astro",
"versions": [
{
"status": "affected",
"version": ">= 1.0.0, < 4.0.19"
}
]
}
]
}
],
"published": "2026-07-27T21:17:05.700",
"references": [
{
"url": "https://github.com/withastro/astro/commit/fbcfa039dfe3d700b239f595a6c55ee35e45bd06",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/withastro/astro/pull/17209",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/withastro/astro/releases/tag/@astrojs/rss@4.0.19",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/withastro/astro/security/advisories/GHSA-8j5q-mfj2-5q9q",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/withastro/astro/security/advisories/GHSA-8j5q-mfj2-5q9q",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
}
],
"vulnStatus": "Deferred",
"weaknesses": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"description": [
{
"lang": "en",
"value": "CWE-91"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"lastModified": "2026-07-28T16:17:16.127",
"sourceIdentifier": "security-advisories@github.com"
}