Vulnerability · Published Jul 27, 2026 · Assigned by GitHub_M
CVE-2026-59727Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands
Low 2.1
In plain English
A low-severity cross-site scripting in astro from withastro. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Astro is a web framework for content-driven websites. In versions 3.10.0 through 7.0.3, when a transition:persist, transition:scope, or transition:persist-props directive is applied to a client-hydrated (client:*) component, Astro copied the directive value onto the rendered <astro-island> element without HTML-escaping it. If a developer reflects attacker-controlled input into one of these directives, an attacker can break out of the attribute and inject arbitrary HTML/JavaScript into the server-rendered output, resulting in reflected cross-site scripting (XSS). Exploitation requires the application developer to have written a non-idiomatic pattern — passing untrusted, request-derived input directly into a transition directive. Astro applications that do not route untrusted input into these directives are unaffected. This issue has been fixed in version 7.0.4.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | astro | 7.0.4 | GHSA-7pw4-f3q4-r2p2 |
Affected products (as reported)
Weakness: CWE-79, CWE-83, CWE-116 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
References
- https://github.com/withastro/astro/security/advisories/GHSA-7pw4-f3q4-r2p2 x_refsource_CONFIRM
- https://github.com/withastro/astro/pull/17212 x_refsource_MISC
- https://github.com/withastro/astro/commit/7ba0bb1dc7516e88caff9abd7767322af44b0294 x_refsource_MISC
- https://github.com/withastro/astro/releases/tag/astro@7.0.4 x_refsource_MISC