CVE-2026-42599
Medium · 6.1CVSS
6.1
EPSS
0.2%
Published
Jun 9, 2026
CISA due date
—
The record
Svelte is a performance oriented web framework. Prior to version 5.55.7, 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. This issue has been patched in version 5.55.7.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| npm | svelte | 0 | 5.55.7 |
Related vulnerabilities
- GHSA-pr6f-5x2q-rwfp Svelte SSR vulnerable to cross-site scripting via spread attributes Same vulnerability
- CVE-2026-42567 Svelte is a performance oriented web framework. Also affects svelte
- CVE-2026-42573 Svelte is a performance oriented web framework. Also affects svelte
- GHSA-f3cj-j4f6-wq85 Svelte: SSR XSS via Insecure Promise Serialization in hydratable Also affects svelte
- GHSA-rcqx-6q8c-2c42 Svelte Vulnerable to XSS via DOM Clobbering of Internal Framework State Also affects svelte
- GHSA-9rmh-mm8f-r9h6 Svelte: ReDoS in `` Tag Validation Also affects svelte
- GHSA-qgvg-pr8v-6rr3 Svelte: XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers Also affects svelte
- GHSA-phwv-c562-gvmh Svelte vulnerable to XSS during SSR with contenteditable `bind:innerText` and… Also affects svelte