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.
References (1)
Core 1
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/withastro/astro/security/advisories/GHSA-8hv8-536x-4wqp
Scores
CVSS v3
7.1
EPSS
0.0027
EPSS Percentile
18.8%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
no
Technical Impact
partial
Details
CWE
CWE-80
Status
published
Products (2)
astro/astro
< 6.3.3
withastro/astro
< 6.3.3
Published
Jun 22, 2026
Tracked Since
Jun 23, 2026