{"id":"GHSA-pr6f-5x2q-rwfp","summary":"Svelte SSR vulnerable to cross-site scripting via spread attributes","details":"When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. Note that this vulnerability _only_ triggers if the user's browser has JavaScript enabled but Svelte's hydration mechanism does not reach the vulnerable element before the event fires.\n\nThis is similar to but different from [CVE-2026-27121](https://nvd.nist.gov/vuln/detail/CVE-2026-27121).","aliases":["CVE-2026-42599"],"modified":"2026-06-09T18:45:27.163431236Z","published":"2026-05-14T20:19:42Z","database_specific":{"github_reviewed_at":"2026-05-14T20:19:42Z","nvd_published_at":"2026-06-09T17:17:07Z","cwe_ids":["CWE-79"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/sveltejs/svelte/security/advisories/GHSA-pr6f-5x2q-rwfp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27121"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42599"},{"type":"PACKAGE","url":"https://github.com/sveltejs/svelte"},{"type":"WEB","url":"https://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7"}],"affected":[{"package":{"name":"svelte","ecosystem":"npm","purl":"pkg:npm/svelte"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.55.7"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 5.55.6","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/05/GHSA-pr6f-5x2q-rwfp/GHSA-pr6f-5x2q-rwfp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N"}]}