Astro is a web framework for content-driven websites. From 2.9.0 until 7.1.0, Astro's server-side View Transition CSS generator interpolates animation properties into an inline style element without escaping them for CSS and HTML contexts. An attacker-controlled View Transition animation value such as duration can terminate the generated style element and inject arbitrary HTML or JavaScript. The affected code is packages/astro/src/runtime/server/transition.ts; renderTransition passes sheet.toString() into markHTMLString(), while addAnimationProperty serializes duration through toTimeValue() and also handles easing, direction, delay, fillMode, and name. Exploitation requires an on-demand or server-rendered route to pass attacker-controlled data into a View Transition animation definition and can execute arbitrary JavaScript in the affected application's origin, allowing access to sensitive page data and authenticated actions available to the victim. This issue is fixed in version 7.1.0.
Advisories
| Source | ID | Title |
|---|---|---|
Github GHSA |
GHSA-4g3v-8h47-v7g6 | Astro: Reflected XSS via unescaped View Transition animation properties |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 12 Aug 2026 21:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Withastro
Withastro astro |
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| Vendors & Products |
Withastro
Withastro astro |
Wed, 12 Aug 2026 20:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Astro is a web framework for content-driven websites. From 2.9.0 until 7.1.0, Astro's server-side View Transition CSS generator interpolates animation properties into an inline style element without escaping them for CSS and HTML contexts. An attacker-controlled View Transition animation value such as duration can terminate the generated style element and inject arbitrary HTML or JavaScript. The affected code is packages/astro/src/runtime/server/transition.ts; renderTransition passes sheet.toString() into markHTMLString(), while addAnimationProperty serializes duration through toTimeValue() and also handles easing, direction, delay, fillMode, and name. Exploitation requires an on-demand or server-rendered route to pass attacker-controlled data into a View Transition animation definition and can execute arbitrary JavaScript in the affected application's origin, allowing access to sensitive page data and authenticated actions available to the victim. This issue is fixed in version 7.1.0. | |
| Title | Astro: Reflected XSS via unescaped View Transition animation properties | |
| Weaknesses | CWE-79 | |
| References |
| |
| Metrics |
cvssV4_0
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Projects
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-08-12T20:32:56.729Z
Reserved: 2026-08-12T14:32:11.795Z
Link: CVE-2026-73422
No data.
Status : Received
Published: 2026-08-12T21:17:41.187
Modified: 2026-08-12T21:17:41.187
Link: CVE-2026-73422
No data.
OpenCVE Enrichment
Updated: 2026-08-12T21:30:07Z
Weaknesses
Github GHSA