{"cve":"CVE-2026-73422","nvd":{"published":"2026-08-12T21:17:41.187","modified":"2026-10-24T15:10:00.190","status":"Deferred","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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N","score":5.3},"cvss_v3":null,"cwes":["CWE-79"],"references":["https://github.com/withastro/astro/commit/092da560eea77ee63a3e2c583c80d8238544e42b","https://github.com/withastro/astro/pull/17393","https://github.com/withastro/astro/releases/tag/astro@7.1.0","https://github.com/withastro/astro/security/advisories/GHSA-4g3v-8h47-v7g6","https://github.com/withastro/astro/security/advisories/GHSA-4g3v-8h47-v7g6"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:35.584907681+00:00"},"epss":{"cve":"CVE-2026-73422","score":0.00547,"percentile":0.45581,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-4g3v-8h47-v7g6","url":"https://osv.dev/vulnerability/GHSA-4g3v-8h47-v7g6","summary":"Astro: Reflected XSS via unescaped View Transition animation properties","modified":"2026-08-12T20:56:01.810465Z","packages":[{"ecosystem":"npm","name":"astro","purl":"pkg:npm/astro","ranges":[">=2.9.0 <7.1.0"],"fixed":["7.1.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}