CVE-2025-64764: Astro is vulnerable to Reflected XSS via the server islands feature

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-11-19 · updated 2026-10-18
Weakness: CWE-80

Description

Astro is a web framework. Prior to version 5.15.8, a reflected XSS vulnerability is present when the server islands feature is used in the targeted application, regardless of what was intended by the component template(s). This issue has been patched in version 5.15.8.

Affected products

withastro astro: before 5.15.8 — fixed in 5.15.8

How to fix

Upgrade to a fixed version: withastro astro 5.15.8. Check the vendor advisory for mitigations.

References

https://github.com/withastro/astro/commit/790d9425f39bbbb462f1c27615781cd965009f91
https://github.com/withastro/astro/security/advisories/GHSA-wrwg-2hg8-v723

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