XSS in Withastro Astro

CVE-2026-114128

Astro is a web framework for content-driven websites. Prior to 7.3.2, Astro's JSX and MDX rendering pipeline treats string children of script and style elements as trusted HTML without distinguishing compiler-generated literal content from dynamic expression values. An application that passes attacker-controlled data directly as a dynamic child can allow a value containing a closing script or style tag to terminate the element and inject arbitrary HTML and JavaScript. Other JSX expression contexts escape dynamic strings automatically; the issue is limited to script and style children rendered through the astro:jsx renderer, including MDX components. Successful exploitation can produce reflected or stored cross-site scripting under the application's origin. This issue is fixed in 7.3.2.

Vulnerability class: XSS (Cross-Site Scripting)

Published .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-114128?
CVE-2026-114128 is a medium-severity vulnerability in Withastro Astro, classified under Cross-site Scripting. CVSS score: 6.5/10. Published 2026-10-21.
How severe is CVE-2026-114128?
Medium severity. CVSS v3 base score is 6.5 out of 10.