Astro is a web framework. Prior to 6.3.3, when a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without HTML escaping the slot name allowing an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected XSS during SSR. This vulnerability is fixed in 6.3.3.
History

Mon, 22 Jun 2026 21:30:00 +0000

Type Values Removed Values Added
First Time appeared Withastro
Withastro astro
Vendors & Products Withastro
Withastro astro

Mon, 22 Jun 2026 18:45:00 +0000

Type Values Removed Values Added
Description Astro is a web framework. Prior to 6.3.3, when a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without HTML escaping the slot name allowing an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected XSS during SSR. This vulnerability is fixed in 6.3.3.
Title Astro: Reflected XSS via unescaped slot name
Weaknesses CWE-80
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-22T17:31:56.313Z

Reserved: 2026-06-03T18:49:32.276Z

Link: CVE-2026-50146

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-22T21:15:04Z