Vulnerability · Published Jun 9, 2026 · Assigned by GitHub_M
CVE-2026-42567Svelte: ReDoS in `<svelte:element>` Tag Validation
Medium 5.9
In plain English
A medium-severity regular-expression denial of service in svelte from sveltejs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)5.9Medium
Exploit odds (30 days)0.5%top 60.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Svelte is a performance oriented web framework. From version 5.51.5 to before version 5.55.7, an internal regex in the Svelte runtime can take exponential time to test in <svelte:element this={tag}></svelte:element>. This issue has been patched in version 5.55.7.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | svelte | 5.55.7 | GHSA-9rmh-mm8f-r9h6 |
Affected products (as reported)
Weakness: CWE-1333 · Vector: 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
References
- https://github.com/sveltejs/svelte/security/advisories/GHSA-9rmh-mm8f-r9h6 x_refsource_CONFIRM
- https://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7 x_refsource_MISC