CVE-2026-59727

Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands

Published Jul 27, 2026 CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-7pw4-f3q4-r2p2 Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Withastro
Withastro astro
Vendors & Products Withastro
Withastro astro
Type Values Removed Values Added
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.
Title Astro: Cross-site scripting via unescaped transition:* directive values on hydrated islands
Weaknesses CWE-116
CWE-79
CWE-83
References
Metrics cvssV4_0

{'score': 2.1, '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 28, 2026, 3:20 PM
Reserved
Jul 6, 2026, 3:34 PM
Status
Deferred
Published
Jul 27, 2026, 8:16 PM
Modified
Oct 24, 2026, 1:10 PM