Vulnerability in Svelte
CVE-2026-42567
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (35.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 35.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.004 · change: -0.000
Affected products
- Svelte
- Sveltejs Svelte — versions >= 5.51.5, < 5.55.7
Weakness classification (CWE)
References
- github.com/sveltejs/svelte/releases/tag/svelte@5.55.7 (Product, Release Notes)
- github.com/sveltejs/svelte/security/advisories/GHSA-9rmh-mm8f-r9h6 (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-42567?
- CVE-2026-42567 is a high-severity vulnerability in Svelte, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-06-09.
- How severe is CVE-2026-42567?
- High severity. CVSS v3 base score is 7.5 out of 10.