CVE-2026-42567
Svelte: ReDoS in `<svelte:element>` Tag Validation
Published: 5/14/2026Modified: 5/14/2026
Description
An internal regex in the Svelte runtime can take exponential time to test in `<svelte:element this={tag}></svelte:element>`. You are only vulnerable to this if you allow tags of unconstrained length. If your application only allows a predetermined list of tags or trims their length before passing them to `svelte:element`, you are safe.
Affected packages (1)
- npm/svelte>= 5.51.5, < 5.55.7
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |